,transcriber's ,notes3 ,underscores 80 before and after a word or phrase indicate italics in the original text4 ,small capitals have been converted to ,,solid capitals4 ,illustrations have been moved so they do not break up paragraphs4 ,old or antiquated spellings have been preserved4 ,typographical errors have been silently corrected but other variations in spelling and punctuation remain unaltered4 ,added 8,spodumene #if0 to ,,toc1 as it was missing4 ,a ,,hand-,,book ,,of ,,precious ,,stones ,,by ,m4 ,d4 ,,rothschild ,,new ,,york ,,london ,g4 ,p4 ,,putnam',s ,,sons ,the ,knickerbocker ,press #ahij ,,copyright ,,by ,m4 ,d4 ,,rothschild #ahhi ,the ,knickerbocker ,press1 ,new ,york ,electrotyped and ,printed by ,g4 ,p4 ,putnam's ,sons ,,contents4 ,,page ,what are ,precious ,stones8 #g ,physical ,characters-- ,crystallization #aj ,cleavage #aj ,fracture #aa ,optical ,properties-- ,refraction #ab ,polarization of ,light #ac ,pleiochroism #ad ,colors #ae ,lustre #ag ,streak #ah ,hardness #ai ,specific ,gravity #ba ,weight #bg ,fusibility #bh ,magnetism #cj ,transparency #cj ,phosphorescence #ca ,electricity #ca ,cutting and ,polishing #cb ,diamond #ce ,corundum #ci ,the ,ruby #dj ,sapphire #dc ,fancy ,sapphires #dd ,star ,sapphires #de ,spinel #df ,beryl #ej ,emerald #ea ,beryl #ec ,chrysoberyl #ed ,cymophane #ef ,alexandrite #ef ,zircon #eh ,turquois #fj ,tourmaline #fd ,opal #fi ,pearl #ga ,chrysolite #gh ,garnet #hj ,topaz #hd ,apatite #hg ,felspar #hh ,moonstone #hi ,sunstone 7,avanturine ,felspar7 #ij ,amazon ,stone 7,green ,felspar7 #ia ,labradorite #ia ,cyanite #ic ,lapis ,lazuli #id ,hiddenite #ie ,spodumene #if ,dichroite #ig ,idocrase #ih ,euclase #ii ,sphene #ajj ,phenacite #aja ,epidote #aja ,axinite #ajb ,diopside #ajc ,fluor ,spar #ajd ,hypersthene #aje ,quartz #ajf ,crystallized ,quartz #aji ,amethyst #aaj ,yellow ,quartz #aaa ,cairngorm1 etc #aaa ,rose ,quartz #aac ,avanturine #aad ,cat's-,eye #aad ,crocidolite #aae ,heliotrope #aaf ,chrysoprase #aag ,prase #aag ,plasma #aah ,chalcedony #aah ,agates #aai ,onyx or ,agate ,onyx #abj ,carnelian #abb ,jasper #abc ,false ,lapis #abd ,hematite #abd ,obsidian #abe ,malachite #abf ,jet #abh ,amber #abh ,coral #acj ,table of ,hardness and ,specific ,gravity #acb ,index #ace ,,preface4 ,the object of this little book is to convey to the merchant1 the workman1 and the amateur1 in a condensed and accurate form1 information concerning the various properties of precious stones4 ,besides drawing freely on a number of authorities1 the author has used his practical experience to indicate such tests as an amateur can readily make4 ,specific gravity1 hardness1 and dichroism are tests which are easily mastered1 and a thorough understanding of these three properties will assist in classifying doubtful gems4 ,such stones have been dealt with principally as are used in commerce for jewelry and ornamental purposes4 ,the attention of the writer has often been called to the general lack of knowledge among the jewelers regarding precious stones other than diamonds1 rubies1 sapphires1 and emeralds4 ,as there are so many other beautiful and rare gems which nature yields to man1 and which are worthy of the jewelers' art1 the author trusts that his book will awaken a new interest in the fascinating study of mineralogy as applied to precious stones1 and that at some future day he may feel encouraged to enlarge upon this treatise4 ,m4 ,d4 ,,rothschild4 #da and #dc ,,maiden ,,lane1 ,,new ,,york4 ,,hand-,,book ,,of ,,precious ,,stones4 ,,what ,,are ,,precious ,,stones8 ,the mineral to which the term 8precious stone0 is applied1 must be adaptable for jewelry or ornamental purposes and must possess beauty1 hardness1 and rarity4 ,the beauty of a precious stone or gem consists of its color or colorlessness1 brilliancy or softness of lustre1 and transparency4 ,to take a high and lasting polish1 a mineral must be hard1--and many stones that would otherwise be highly valued are low in the estimate of worth because they do not possess of sufficient hardness to make them endure the wear and friction to which a precious stone is subjected when used in the form of jewelry4 ,the rareness of precious stones has a decided effect in determining their values4 ,for instance1 the crocidolite1 commercially known as tiger-eye1 was sold by the carat some years ago1 and was largely used in the making of fine jewelry4 ,to-day1 this material is so plentiful that it is no longer classed among the higher gems1 but serves for cameos and intaglios like chalcedony and onyx4 ,the changes of fashion have much to do with determining the market value of precious stones4 ,amethysts1 topazes1 cat's-eyes1 aquamarines1 alexandrites1 and even emeralds and opals have been eagerly sought for at times and then again neglected for other gems1 causing a sensible difference in the value of these stones4 ,there are all degrees of precious stones1 from the valuable diamond and corundums to the humbler quartz1 amethyst1 and topaz4 ,it has been a mooted question as to the proper dividing line between stones that deserve the title 8precious10 and those which should be placed in a so-called semi-precious or lower category4 ,to draw such a line is hardly possible1 as neither hardness1 rareness1 nor value would be a positive test--some of the hard stones1 like zircon and almandines being less valuable than the softer opal1 while the diamond1 one of the most plentiful of precious stones1 is at the same time1 one of the most valuable4 ,neither can price be taken as a complete test1 because fashion makes a turquois1 an opal1 or an emerald much more valuable at one time than at another4 ,all precious minerals used for ornamental purposes1 from the diamond to quartz1 or chalcedony1 may properly be termed precious stones4 ,,physical ,,characters4 ,,crystallization4 ,precious stones are found either in crystallized or amorphous conditions4 ,the forms of crystallization are3 #a ,isometric or ,cubic2 having the axes equal4 #b ,tetragonal or ,pyramidal having only the #c ,hexagonal or ,rhombohedral lateral axes equal4 #d ,orthorhombic or ,trimetric #e ,monoclinic or ,oblique having the axes #f ,triclinic or ,anorthic unequal4 ,most precious stones crystallize1 but the specimens that have the crystallization clearly defined are seldom found4 ,the amorphous condition includes the turquois1 opal1 and obsidian1 which minerals are found in masses or veins surrounded by a matrix4 ,,cleavage4 ,many minerals can be separated readily in one direction by simply making a small indentation with a harder mineral1 then introducing the blade of a knife into the scratch and striking it a sharp blow1--this separates the crystal4 ,there are certain planes at right angles where the crystal can be separated2 this property is called cleavage and the planes1 cleavage planes4 ,in some minerals cleavage is difficult to produce1 while in others such as mica and rock-salt1 cleavage is highly perfect and the number of separations produced is only limited by the thickness of the blade used in separating the planes4 ,the property of cleavage is very useful and of great assistance to the lapidary1 as it enables him to shape a diamond or other hard stone nearly to the size he desires1 and at the same time to save the extra material cleaved off1 which can be used for smaller gems1 and which under other conditions would have to be ground away4 ,,fracture4 ,fracture surfaces are the result of the breaking of a crystal otherwise than by cleaving1 and in a different direction from the cleavage planes4 ,when the form of fracture is composed of concave and convex surfaces it is called conchoidal2 when free from inequalities it is known as even or smooth1 and when covered by small splinters1 splintery or uneven4 ,,optical ,,properties4 ,,refraction4 ,when a ray of light passes from one medium to another1 or from the air to a crystal it is bent or refracted2 this is called single refraction and takes place in the diamond1 spinel1 and garnet4 ,most of the other transparent precious stones possess double refraction--that is1 the ray of light enters the crystal and divides into two parts1 one following the ordinary laws of refraction1 while the other part or extraordinary ray does not obey the usual law4 ,there are precise methods for measuring the indices of refraction1 but they are not applicable to polished gem stones4 ,,polarization ,,of ,,light4 ,polarization is a peculiar modification which1 under certain conditions1 a ray of light undergoes4 ,this property is easier to observe than double refraction4 ,if from a transparent prism of tourmaline two thin plates are cut1 parallel to its axis1 they will transmit light when they are placed above each other with the chief axis of each in the same direction4 ,when one of the plates is turned at right angles to the other1 no light1 or but very little1 is transmitted1 so that the plates appear black4 ,in passing through the first slip1 the rays of light have acquired a peculiar property1 which renders them incapable of being transmitted through the second1 except when the two are held in a parallel position1 and the rays are then said to be polarized4 ,in some doubly refracting crystals the two oppositely polarized beams are of different colors1 so upon double refraction and polarization depends the property of many gems which is called pleiochroism4 ,,pleiochroism4 ,the dichroiscope is a handy little optical instrument1 that will readily serve to distinguish the diamond1 spinel1 or garnet 7all singly refracting minerals7 from the ruby1 beryl1 or any of the doubly refracting stones4 ,this instrument consists of a cleavage rhombohedron of ,iceland spar1 fastened in a brass tube about #b inches long1 and of an inch in diameter4 ,a sliding cap at one end has a perforation of an inch square1 and at the other end is a lens which will show a distinct image of the square opening when the cap is pulled out about of an inch4 ,illustration3 ,,fig4 #a4 ,the pleiochroism of many stones can be determined at a glance with the dichroiscope4 ,when a stone is examined by means of the dichroiscope1 it will show two images of the same hue1 or of different hues1 these square images 7fig4 #a1 ,a7 forming a right angle and being more distinct when viewed from one part of the stone than from another4 ,when the images are identical in color1 the specimen may be a diamond1 garnet1 spinel1 or glass4 ,should a red or ruby spinel approach the ruby in color1 a quick and satisfactory test can be made with the dichroiscope1 as the spinel will show two images of one color1 while the ruby will show one image of aurora red and one of carmine red4 ,the dichroiscope is inexpensive1 costing but a few dollars1 and is very useful for rapidly deciding the species of many stones4 ,the following is a partial list of doubly refracting stones and their twin colors4 ,,name ,,of ,,stone4 ,,twin ,,colors4 ,sapphire 7blue7 ,greenish straw ,blue ,ruby 7red7 ,aurora red ,carmine red ,tourmaline 7red7 ,salmon ,rose pink 7brownish red7 ,umber brown ,columbine pink 7brown7 ,orange brown ,greenish yellow 7green7 ,pistachio green ,bluish green 7blue7 ,greenish gray ,indigo blue ,emerald 7green7 ,yellowish green ,bluish green ,topaz 7sherry7 ,straw yellow ,rose pink ,peridot 7pistachio7 ,brown yellow ,sea green ,aquamarine 7sea green7 ,straw white ,gray blue ,beryl 7pale blue7 ,sea green ,azure blue ,chrysoberyl 7yellow7 ,golden brown ,greenish yellow ,iolite 7lavender7 ,pale buff ,indigo blue ,amethyst 7purple7 ,reddish purple ,bluish purple ,,colors4 ,the following is a partial list of the colors of precious stones3 ,shades of ,white4--,quartz1 opal1 chalcedony4 ,shades of ,gray4--,labrador1 smoky topaz1 chalcedony1 zircon4 ,black4--,obsidian1 tourmaline1 jet4 ,shades of ,blue4--,lapis-lazuli1 amethyst1 chalcedony1 spinel1 zircon1 sapphire1 cyanite1 tourmaline1 turquois1 odontolite1 fluor spar4 ,shades of ,green4--,amazon stone1 turquois1 prase1 beryl1 blood-stone1 epidote1 emerald1 malachite1 chrysoprase1 chrysolite1 idocrase1 olivine1 garnet1 chrysoberyl4 ,shades of ,yellow4--,opal1 amber1 topaz1 beryl1 jasper4 ,shades of ,red4--,garnet1 carnelian1 chalcedony1 rose quartz1 corundum1 tourmaline1 spinel1 ruby4 ,shades of ,brown4--,zircon1 garnet1 smoky topaz1 axinite1 jasper4 ,colorless4--,diamond1 sapphire1 spinel1 zircon1 topaz1 rock crystal1 moonstone4 ,,lustre4 ,well polished precious stones display a decided lustre1 which assists in determining their species4 ,the following is a list of some precious stones and their lustre3 ,adamantine4--,diamond1 zircon4 ,resinous4--,garnet4 ,vitreous4--,emerald1 ruby1 spinel4 ,waxy4--,turquois4 ,pearly4--,moonstone1 opal4 ,silky4--,crocidolite1 quartz cat's-eye4 ,metallic4--,hematite4 ,greasy4--,olivine4 ,some stones vary in lustre1 from vitreous to pearly1 etc4 ,,streak4 ,the streak of a mineral is the color of its powder4 ,this powder varies in color1 and may be white1 gray1 red1 etc4 ,it is obtained by scratching the mineral with a sharp file1 or by rubbing the mineral on the back of an unglazed porcelain plate1 when the color of the powder will appear on the plate4 ,it is remarkable that the streak of the diamond is gray to grayish-black1 while that of the ruby is colorless or white4 ,,hardness4 ,one of the most important and distinguishing qualities of a gem stone is the property of enduring1 resisting wear1--in short1 hardness4 ,to test the hardness of precious stones that have not been cut or polished1 the following scale of ten minerals has been devised by ,moh1 a ,german mineralogist3 ,no4 #a4 ,talc4 ,very soft2 is easily broken or scratched with the finger-nail4 ,no4 #b4 ,rock-salt4 ,soft2 scratched with difficulty with finger-nail2 readily cut with a knife4 ,no4 #c4 ,calcite4 ,low degree of hardness2 not to be scratched with finger-nail2 easily scratched with a knife4 ,no4 #d4 ,fluor spar4 ,fairly hard2 is slightly scratched by a knife1 but easily attacked with a file4 ,no4 #e4 ,apatite4 ,medium hardness2 does not scratch glass1 or only faintly2 does not give out sparks against steel2 easily attacked with a file4 ,no4 #f4 ,felspar4 ,easily scratches glass2 is attacked by a file1 and gives some sparks against steel4 ,no4 #g4 ,quartz4 ,quite hard2 is only slightly attacked by file2 gives sparks readily against steel4 ,no4 #h4 ,topaz4 ,very hard2 is not attacked by a file4 ,no4 #i4 ,sapphire4 ,hardest of all minerals but the diamond2 attacks all other minerals4 ,no4 #aj4 ,diamond4 ,attacks all minerals2 is not attacked by any4 ,to find the hardness of a stone1 begin to test with the softest mineral1 so that when the number is reached which will scratch the stone1 there has been no injury to the specimen under examination4 ,half numbers are determined by the ease or difficulty with which a stone is scratched4 ,for example1 a stone which will resist ,no4 #g 7quartz7 and which is only faintly attacked by ,no4 #h 7topaz7 may be safely put down as #g4e1 while a stone which resisted ,no4 #g and yielded easily to ,no4 #h is to be classed as #g in hardness4 ,these tests are readily applied to crystals or unpolished gems4 ,with the polished stone greater care must be observed1 and while a file test is often satisfactory1 there is always the danger of striking the cleavage and breaking off a small piece of the stone4 ,,specific ,,gravity4 ,one of the most important tests which can be applied to a polished stone is that of specific gravity4 ,many stones1 like the ruby and the spinel1 the blue tourmaline and the sapphire1 etc41 look alike1 but there is a sensible difference in their respective weights that a specific-gravity test will readily establish4 ,the weight of an object which is free to seek the centre of gravitation is called absolute weight1 while the weight of an object compared with that of another containing the same volume of matter is called the specific weight4 ,if a stone weighing #af carats is placed in a vessel filled to the brim with distilled water and the stone displaces #f carats of water1 the specific gravity of the stone would be #af #f1 or #b4ff1 the specific gravity of quartz4 ,in other words1 the stone would weigh #af carats in the air and only #aj carats in the distilled water1 showing a loss of #f carats1 which is the weight of the volume of water equal in bulk to the stone2--or absolute weight1 #af carats2 specific weight1 #aj carats2 loss1 #f carats2 #af #f #b4ff1 specific gravity4 ,there are several methods of ascertaining the specific gravity of a stone4 ,first1 by placing it in liquids of known specific gravity4 ,second1 by weighing the stone in air and then in distilled water or alcohol1 and thus learning the weight of an equal bulk of water4 ,third1 by measuring or weighing the water which the stone displaces when immersed in a small vessel of known capacity4 ,fourth1 by means of the ,nicholson hydrometer1 a simple instrument consisting of a hollow glass cylinder1 two dishes1 and a glass vessel4 ,as the jewelers' balances are well adapted for the ordinary work of taking specific gravity1 or can be easily adapted for such work1 the second method will usually be the more practical to follow4 ,the author has had very satisfactory service from a #cj balance1 and any well adjusted balance will give fair results4 ,the following accessories are necessary to take the specific gravity of a stone3 ,distilled water about #fj ,fahr4 ,a very fine thread of platinum wire with which to suspend the stone 7fig4 #d74 ,a glass-beaker for the water 7fig4 #c1 ,c74 ,a bench to hold the beaker over the pan 7fig4 #b74 ,illustration3 ,,fig4 #d4 ,illustration3 ,,fig4 #b4 ,illustration3 ,,fig4 #c4 ,the distilled water is easily obtainable from any druggist4 ,the platinum wire should be bent to hook into the top of the balance frame1 7fig4 #c1 ,b7 and for ordinary small stones it will be convenient to twist the other end into a cork-screw shape or receptacle 7fig4 #d1 ,a74 ,the beaker can be a small1 thin glass cup of any kind1 and the bench is easily produced from wood 7fig4 #b7 or of metal with three supports 7fig4 #c1 ,a74 ,to ascertain the specific gravity1 attach the platinum wire to the balance frame1 7fig4 #c1 ,b7 and allow the lower end to rest in the water2 then balance this carefully by adding weights to the other side 7fig4 #c1 ,d7 until the balance is exact4 ,the stone to be weighed in water is a ruby1 and weighs two carats in the air4 ,clean the stone carefully with water to free it from air bubbles2 then place it in the screw of the wire 7fig4 #d1 ,a7 and weigh carefully4 ,if the stone weighs #a carats it will have displaced ct4 of water3 or1 weight in air1 #b carats2 weight in water1 #a carats2 loss1 carat2 #b #d1 which will be the specific gravity of the ruby4 ,the ,jolly spiral balance can also be used for taking specific gravity1 but it is not so practical or accurate for small stones as for the larger ones4 ,,weight4 ,the valuable precious stones are bought and sold by the carat4 ,this weight is equal to about #c4ag grains or about 4#bje milligrams4 ,the carat is divided into fractions of 1 1 1 #a_/af1 #a_/cb1 #a_/fd1 and also arbitrarily into four grains2 that is1 each quarter of a carat is counted one grain1 thus forming the basis for the calculation of pearls4 ,in commerce1 a carat diamond is sometimes called a four-grain stone1 and a carat-and-a-half stone is six grains1 etc41 etc4 ,the weight of the carat being arbitrary1 it varies in different countries1 some being heavier and others lighter than 4#bje milligrams4 ,the writer wrote to three prominent balance-makers in the ,united ,states some months ago for their carat standards and was surprised to find that they all differed4 ,this will account for discrepancies in weight resulting between the balances of different makers4 ,of late there has been a decided movement in ,europe1 headed by the ,french ,chambre ,syndicale of jewelers1 in favor of the unification of the carat1 so that the weight of a ,french or ,dutch carat will equal that of an ,english1 ,american1 or any other carat4 ,this reform will probably be accompanied by the adoption of the decimal system of dividing the carat1 and the discarding of the complicated fractional system4 ,after having tried the decimal weights for many months1 the author can testify to a decided gain in time and accuracy from their use4 ,,fusibility4 ,the blow-pipe or dry test for minerals is convenient to apply to small bits or splinters of a stone4 ,the mineral is either held by a pair of platina-pointed forceps1 or powdered and placed on a metal plate or in a glass tube4 ,before the blow-pipe1 some minerals change color1 but do not melt1 while others retain their color1 or swell up1 or break into small particles1 or melt into colorless or colored glasses4 ,the following is the scale of minerals used to test the different degrees of fusibility3 #a4 ,gray ,antimony4 ,fusible in coarse splinters in summit of candle flame without the blow-pipe4 #b4 ,natrolite4 ,fusible in fine splinters in the summit of a candle flame without the blow-pipe4 #c4 ,almandite4 ,does not fuse in candle flame2 fuses easily before the blow-pipe in obtuse pieces4 #d4 ,green ,actinolite4 ,fusible before the blow-pipe in coarse splinters4 #e4 ,orthoclase4 ,fusible before the blow-pipe in fine splinters4 #f4 ,bronzite4 ,before the blow-pipe becomes rounded only on the sharp edges4 ,,magnetism4 ,there are but few precious stones that possess the power to act on the magnetic needle2 among them are the chrysolite1 cinnamon stone1 almandine1 pyrope1 and garnet4 ,,transparency4 ,precious stones are1 on the basis of their relative transparency1 divided into four classes1 as follows3 ,transparent1 or admitting light freely and clearly2 defining objects when used as a lens4 ,semi-transparent1 admitting light1 but only partially defining objects4 ,translucent1 admitting light faintly4 ,opaque1 not admitting light4 ,the more valuable precious stones1 excepting opals and turquoises1 are generally transparent4 ,,phosphorescence4 ,some precious stones display a distinct phosphorescence after exposure to the sunlight1 and also upon the application of artificial heat1 and through mechanical and electrical means4 ,many diamonds1 when taken to a dark room1 appear quite luminous2 this is also true of topaz1 fluor spar1 and other minerals4 ,,electricity4 ,minerals acquire electricity through friction or heating1 and in this state readily attract or repel small bits of paper and other light substances4 ,all minerals are electric1 some displaying positive and others negative electricity4 ,the electric test of a precious stone refers to the length of time that a stone will retain electricity after friction or heating4 ,some stones lose this quality in a few minutes1 while others retain it a long time4 ,the tourmaline is noted for its electrical properties1 while the ,brazilian topaz rendered electric by heating or rubbing has been known to affect the electric needle after #cb hours4 ,,cutting ,,and ,,polishing4 ,although a finely developed diamond1 ruby1 or other crystal is sometimes found and used for jewelry1 the beauty of a precious stone generally remains hidden within a rough and unsightly exterior until the lapidary's art reveals the gem4 ,according to well known rules1 there is one kind of cutting or faceting for the diamond or colorless gems and another for colored gems4 ,the brilliant cut1 figs4 #e and #f1 consists of an arrangement of fifty-six facets1 exclusive of the table and culet4 ,this cut is sometimes improved by the addition of eight star facets around the culet1 which brings the number of facets up to sixty-four4 ,the following are the proportions of a well cut diamond or colorless gem3 above the girdle1 fig4 #f1 ,a4 below #f1 ,b4 ,the table #b_/e of the breadth of the stone1 fig4 #f1 ,c4 ,the culet of the size of the table1 fig4 #f1 ,d4 ,illustration3 ,,fig4 #e4 ,,fig4 #f4 ,these proportions do not refer to colored gems1 which are cut thick or shallow to deepen or diminish the color of the stone4 ,the step cut1 fig4 #g1 now principally used for emeralds1 can be advantageously used for other colored stones4 ,the crowned rose cut1 fig4 #h1 is applied to small diamonds1 and occasionally to colored gems4 ,this cut consists of twenty-four facets1 and a well proportioned rose is one half of its diameter in thickness4 ,illustration3 ,,fig4 #g4 ,,fig4 #h4 ,illustration3 ,,fig4 #i4 ,,fig4 #aj4 ,to the smaller and more common roses only twelve facets are given4 ,besides the above-mentioned forms1 there are the3 ,huitpan1 or single cut4 #af facet double #bd single brilliant4 ,cabochon carbuncle4 ,star cut1 fig4 #i4 ,degree or rose cut1 fig4 #aj4 ,the last two beautiful forms of cutting are frequently given to fine paste or imitation diamonds4 ,of late years nearly all gems have been cut quite round1 and in many instances with a sacrifice of size and brilliancy4 ,,diamond4 ,the diamond is one of the most precious minerals1 and yet it consists of pure carbon1 the most common substance that is known1 a substance that is present in all animal and vegetable bodies and in the larger number of minerals4 ,when carbon is crystallized the result is the diamond1 which is always found in detached crystals1 either octahedrons or rhombic dodecahedrons1 the planes of the angles being often convex or rounded1--this curving crystal being peculiar to the diamond4 ,the cleavage is perfect1 and1 parallel to the faces of the octahedron1 the fracture is conchoidal or curved4 ,the diamond is not acted upon by acids or alkalies1 is infusible but combustible1 and burns under heat of a very high temperature4 ,diamond powder burns readily1 but larger pieces are not affected by the blow-pipe4 ,the diamond is a non-conductor of electricity1 but acquires positive electricity when rubbed1 and retains it for half an hour4 ,after being exposed to the solar rays1 the diamond presents a distinct phosphorescence in the dark4 ,it possesses single refraction1 but belongs to those bodies which reflect light most strongly1 and its magnifying power is much greater than that of glass2 it does not polarize light2 its lustre is adamantine1 and specific gravity #c4e to #c4f4 ,the diamond is the hardest of all known minerals1 ranking ,no4 #aj in ,moh's scale of hardness4 ,white1 and the different shades from very light yellow to dark yellow or canary1 comprise1 according to the popular idea1 the colors of the diamond4 ,yet the diamond is found in green1 red1 blue1 brown1 olive1 orange1 and black1 and also in the various shadings of these colors and in opalescent tints4 ,as the limpid or white diamond surpasses all other white stones in the power of its lustre and the magnificence of its fire1 so do the colored diamonds outrank the emerald1 ruby1 sapphire1 and other gems of like colors4 ,colored diamonds1 excepting light yellow and brown1 are rare1 and hence are the most valuable of precious stones4 ,the limpid or perfectly white and the white with a bluish tint are the most sought after1 while fine deep golden yellow or canaries and pronounced fancy colors always find a ready market4 ,diamonds come principally from the mines in ,south ,africa2 some are found in ,brazil and ,india1 and fewer in ,sumatra1 ,borneo1 the ,ural ,mountains1 and ,australia4 ,crystals have also been found in the ,united ,states4 ,the amorphous or carbon diamond is found only in ,brazil4 ,the pebbles or masses are opaque1 steel-gray to black in color1 and sometimes weigh #a1jjj carats4 ,this carbonate is principally used to point rock-drills and for other engineering purposes4 ,the coarse variety of crystallized diamonds is called bort1 and as this is unfitted for gem purposes because of imperfections1 it is ground into powder and used for cutting and drilling precious stones4 ,white sapphires1 white zircons1 white topaz1 and rock-crystal sometimes pass for diamonds4 ,the first two are heavier1 the topaz lacks brilliancy1 and the crystal is lighter than the diamond4 ,it is also the case that these four stones1 especially the crystal1 are easily scratched by a diamond4 ,the best style of cutting for a diamond is the brilliant1 of #ff facets1 including the table and culet4 ,the proper proportions of a well cut brilliant is for the crown and for the culet4 ,the table and culet must also be in proportion to the size of the stone4 ,,corundum4 ,this many-colored mineral1 composed of nearly pure alumina1 produces gems which in some cases are more valuable even than diamonds4 ,the ruby1 sapphire1 ,oriental emerald1 ,oriental topaz1 ,oriental amethyst1 ,oriental aquamarine1 ,oriental chrysolite1 ,oriental hyacinth1 star ruby1 star sapphire1 star topaz1 and ruby and sapphire cat's-eyes are all corundums of different colors4 ,the ruby is a red sapphire1 and the ,oriental topaz a yellow sapphire1 while the ,oriental emerald is a green sapphire1 etc41 etc4 ,in hardness corundum ranks next to the diamond1 ranking ,no4 #i in ,moh's scale4 ,the specific gravity is #c4i to #d4a1 the crystallization rhombohedral1 and cleavage basal1 the crystals breaking across the prism with nearly a flat surface4 ,in lustre1 the corundum is vitreous1 its refraction double but not to a high degree1 and it is susceptible of electricity by friction1 which the polished specimens especially retain for a considerable time4 ,corundum is unaffected by chemicals1 and is infusible alone1 but in combination with a flux it melts with difficulty into a clear glass4 ,the chemical composition of precious corundum is3 ,alumina #ih4e ,oxide of iron #a4j ,lime #j4e #ajj4 ,thus it will be seen that corundum is composed almost wholly of alumina1--one of the constituents of common clay1 which1 when colored by traces of metallic oxides1 chrome1 etc41 produces a greater variety of precious stones of a high rank than any other mineral4 ,,the ,,ruby4 ,the red sapphire or ruby is the most valuable of the corundum family1 and when found of a good color1 pure and brilliant1 and in sizes of one carat and larger1 it is much more valuable than a fine diamond of the same size4 ,fine rubies larger than #a to #b carats are very rare1 and when a fine stone from #c to #e carats is offered for sale1 the price mounts into the thousands4 ,the color varies from the lightest rose tint to the deepest carmine2 that color1 however1 which has the greatest value is known in commerce as pigeon's blood1 and is the color of arterial blood1 or of the very centre of the red ray in the solar spectrum4 ,the imperfections in rubies1 as in all corundums1 consist largely of clouds1 milky spots1 and cracks4 ,a perfect ruby is rarely met with1 and a stone possessing brilliancy and the true color1 even if slightly defective1 is considered more valuable than an absolutely perfect ruby of an inferior color4 ,rubies are found in ,siam1 ,ceylon1 ,burmah1 ,brazil1 ,hindustan1 ,borneo1 ,sumatra1 ,australia1 ,france1 and ,germany4 ,where rubies and sapphires are met with it is said that gold is almost sure to be present4 ,chemists have succeeded in producing minute crystals of rubies and sapphires which1 under the microscope1 presented the true crystallization of corundums1 and upon being tested proved to be of the same hardness as rubies and sapphires2 but these specimens were small1 and cost very much more to produce than their commercial value4 ,ruby spinels1 garnets1 hyacinths1 red quartz1 burnt ,brazilian or rose topaz1 and red tourmaline are sometimes passed off for the ruby4 ,the true ruby will scratch all of these stones readily1 the spinel is lighter in specific gravity1 and has generally a slight tinge of yellow1 even in the most pronounced red specimens4 ,the ruby will turn green under the flames of a blow-pipe1 but when cooled off1 resumes its original color4 ,the garnet and topaz are easily scratched by the ruby1 the hyacinth is heavier1 and quartz and tourmaline lighter than the ruby4 ,some so-called reconstructed rubies1 recently offered for sale1 are of a very fine color1 and closely resemble the ,oriental gems4 ,the hardness and specific gravity are the same1 but they differ in one very important point1 namely3 they lack the brilliancy of the true ruby4 ,in addition to this lack of fire1 a microscopical test discloses formations which will distinguish the manufactured from the natural stone4 ,,sapphire4 ,the blue corundum1 ranging in color from the lightest blue to deep blue and black1 is the same stone as the ruby1 the only difference being in the color4 ,the choicest color is the soft velvety blue1 approaching the corn-flower in shade and exhibiting that color vividly by artificial as well as by natural light4 ,the deeper-colored stones are known as male1 and the light-colored ones as female sapphires4 ,although choice sapphires are rare1 a much greater quantity of good and large stones are to be had than of rubies1 and therefore the price of a large sapphire does not advance in the same proportion as the price of a large ruby4 ,,fancy ,,sapphires4 ,the ,oriental emerald or green sapphire does not approach the beryl or true emerald in depth of color1 but because of its superior hardness and brilliancy1 added to its extreme rarity1 it is the most valuable of green gems4 ,the ,oriental amethyst or purple sapphire sometimes reflects a red color by artificial light1 and is valued highly as a gem stone2 the common amethyst is softer1 less brilliant1 and loses by artificial light4 ,the various other colored sapphires1 such as yellow or ,oriental topaz1 light green or ,oriental aquamarine1 greenish-yellow or ,oriental chrysolite1 and aurora-red or ,oriental hyacinth1 are all valuable as gem stones when they are pure1 well cut1 and have pronounced colors--in fact1 the name ,oriental is given to distinguish the corundums from the less valuable minerals of the same colors which they resemble1 but which they greatly surpass in beauty and value because of their brilliancy and superior hardness4 ,,star ,,sapphires4 ,asterias or star stones are corundums of three different colors2 the star sapphire proper is a grayish blue1 the star ruby red1 and the star topaz yellow4 ,these stones are usually cut cabochon or convex1 and display under the rays of the sun1 or when exposed to one candle or other artificial light1 a beautiful star with six points4 ,this star is produced by foreign substances in the corundum1 and the lapidary brings about the regular effect by cutting a pointed carbuncle so that the centre of the star begins at the apex1 and the six bright stripes radiate to the base of the stone4 ,the bright lines of the star following the light move over the surface of the stone and produce a remarkable effect4 ,these stones are amongst the most wonderful of mineral productions1 and good specimens are very valuable4 ,the corundum cat's-eye1 called ,oriental girasol or sunstone1 has a bluish1 reddish1 or yellowish reflection of light of a lighter shade than the stone itself1 and which moves on the convex surface of the stone like the lines of a star stone4 ,,spinel4 ,it is only during the past century that mineralogists make a distinction between the minerals spinel and corundum4 ,the composition of the spinel was discovered towards the end of the last century1 and was found to be about seventy per cent4 alumina1 twenty-five per cent4 magnesia1 and small parts of oxide of chrome1 silica1 and protoxide of iron4 ,up to that time1 red spinels had always been confounded with rubies1 and many celebrated so-called rubies have been shown to be spinels by modern mineralogists4 ,this beautiful mineral is found in many colors1 from pink to rose-red1 carmine1 cochineal1 blood-red1 hyacinth1 pale to dark blue1 violet and indigo blue1 grass-green to blackish green1 and sometimes colorless4 ,there is also a black variety called pleonaste or ceylonite4 ,spinels crystallize in octahedrons and their modifications1 the fracture is conchoidal1 specific gravity #c4e to #c4f1 and hardness ,no4 #h in ,moh's scale2 only the diamond1 corundum and chrysoberyl will scratch the spinel4 ,its refraction is single1 the lustre highly vitreous1 and it does not easily acquire electricity4 ,acids do not attack the spinel1 nor has the blow-pipe any effect on this mineral1 except to change the red to a brownish or colorless state1 but the original color returns when the stone cools4 ,flawed or imperfect stones are liable to crack or split if heated too much4 ,with borax or salt of phosphorus the spinel melts into a colorless or green-tinted glass4 ,spinels are found in clay and in the sands of rivers1 in ,east ,india1 ,hindustan1 the province of ,mysore1 ,farther ,india1 ,pegu1 ,ceylon1 ,north ,america1 ,sweden1 ,bohemia1 and ,australia4 ,the red spinel1 and especially those tints which approach the red corundum or true ruby in color1 are the most valuable1 and are known as ruby spinels4 ,very fine specimens of ruby spinels of one carat and larger are quite rare and command good prices4 ,rose-colored spinels are known as balas-rubies1 pale-blue spinels as sapphirines1 and the hyacinth-red1 yellowish-red1 and orange-yellow spinels are called rubicelles4 ,all these different-colored spinels1 if pure and of great brilliancy1 are valuable as gem stones1 being only surpassed in hardness and brilliancy by the diamond and corundums4 ,the white spinel1 which is seldom found1 is sometimes confounded with the diamond1 having the same specific gravity and single refraction1 but as it lacks the fire and is easily scratched by the diamond1 the danger of mistaking one for the other is slight4 ,burnt amethyst1 which often resembles the spinel1 is lighter and softer1 while burnt topaz1 although it is identical with the spinel in hardness1 is somewhat lighter and possesses remarkable electric powers1 becoming electric by either rubbing1 heating1 or pressure1 and retaining electricity for upwards of twenty-four hours4 ,the zircon is easily distinguished from the spinel because of its much greater specific gravity4 ,it is also doubly refractive and softer4 ,garnets are softer1 lack the play of color and brilliancy1 and fuse easily into a light-brown or black glass4 ,,beryl4 ,the beryl is a mineral belonging to the primitive formation1 and is found in quartz veins and granite4 ,it crystallizes in six-sided prisms and is composed largely of silica1 the third most common of earth's productions4 ,the beryl is #g4e to #h in hardness1 scratching quartz1 but is scratched by topaz4 ,the specific gravity is #b4fg to #b4gc1 making it one of the light minerals4 ,its lustre is vitreous and refraction double to a slight degree2 its cleavage is imperfectly basal1 and it becomes electric by rubbing4 ,acids do not attack the beryl1 but it melts with borax and is soluble in salts of phosphorus4 ,this stone is found in various colors1 grass-green1 pale-green1 light-blue1 greenish-blue1 greenish-yellow1 yellow1 and sometimes pink4 ,the most important of these colors is the grass-green1 which forms a separate division of the beryl family1 and is known as the emerald4 ,,emerald4 ,the emerald or green beryl is one of the most highly prized of the gem stones4 ,its magnificent color has rightly been compared to the color of the fresh grass in spring1 and in brilliancy this stone far exceeds all other green gems1 excepting only the very rare green corundum or green sapphire4 ,the emerald is said to be very soft when first withdrawn from the mine1 but it hardens by exposure to the air4 ,a perfect emerald of fair size is a rarity1 so that the saying 8an emerald without a flaw0 has passed into a proverb4 ,this stone is so light1 compared to a diamond or sapphire1 that a carat emerald will be very much larger than either of the above stones4 ,the emerald is composed of3 ,silica #fh4ej ,alumina #ae4ge ,glucina #ab4ej ,peroxide of iron #a4 ,lime #j4be ,oxide of chrome #j4cj ,and traces of magnesia1 of lime1 and of soda4 ,the vivid green color of the emerald is supposed to come from the oxide of chrome1 as the other beryls do not contain chrome4 ,emeralds are found in ,new ,granada1 near ,bogota1 ,egypt1 ,east ,india1 ,burmah1 ,ural in ,europe2 ,salzburg1 ,austria2 ,mt4 ,remarkable1 ,south ,australia2 and ,north ,america4 ,some of the finest come from the mines of ,muza1 near ,bogota1 and the best stones are called ,peruvian emeralds4 ,during the conquest of ,peru by the ,spaniards1 many very fine emeralds were destroyed by the invaders1 who tested them by grinding and pounding1 and concluded that the emeralds were worthless1 because they were not as hard as the diamonds or sapphires4 ,in #aehg1 ,joseph ,d',acosta returned to ,spain with two cases of emeralds1 each case weighing one hundred pounds4 ,green tourmaline sometimes passes for the emerald1 but it is somewhat softer and considerably heavier4 ,olivines or chrysolites1 if of a fine green color1 sometimes resemble the emerald1 but they are much heavier than the emerald and have a fatty lustre4 ,green spinels are heavier and harder than emeralds4 ,,beryl4 ,the second and less valuable division of the beryl family comprises the following colors3 ,clear light sky-blue1 called by lapidaries aquamarine2 very light greenish-blue1 known as ,siberian aquamarine2 and a greenish-yellow variety1 called aquamarine chrysolite4 ,these three kinds are usually very brilliant1 and especially so by artificial light1 in which respect the beryl is superior to many of the more valuable gem stones4 ,beryls of very large size have been found in ,new ,hampshire1 one of which has been estimated to weigh over two tons4 ,while the large specimens are worthless for gem stones1 some very handsome aquamarines and golden-yellow beryls have been found during the past few years in ,new ,hampshire and ,connecticut4 ,these stones1 when cut1 compare favorably with the best of their kind4 ,,chrysoberyl4 ,the name chrysoberyl is derived from two ,greek words signifying golden-beryl4 ,this name is well suited to the golden-yellow variety1 but the chrysoberyl also includes many other colors3 such as green1 greenish-yellow1 brownish-yellow1 white1 and dark-brown to black4 ,three varieties of chrysoberyls are known as cat's-eyes1 cymophanes1 and alexandrites4 ,the chrysoberyl crystallizes in the trimetric or rhombic system2 the cleavage is imperfect2 fracture conchoidal2 hardness1 #h4e1 being the third hardest stone2 specific gravity1 #c4fe to #c4h2 and lustre vitreous to greasy4 ,the composition of the chrysoberyl is3 alumina1 #hj4b2 glucina1 #ai4h2 with traces of protoxide of iron and oxides of lead and copper4 ,the chrysoberyl is doubly refractive to a high degree1 acquires positive electricity lasting several hours1 is infusible alone1 but melts with borax or salts of phosphorus to a clear glass1 though with difficulty4 ,the chrysoberyl is unaffected by acids1 but with a solution of cobalt nitrate the powdered mineral becomes blue4 ,transparent greenish-yellow chrysoberyls are sometimes called ,oriental chrysolites4 ,these1 and the brownish-yellow stones are the gems most used in jewelry4 ,the chrysoberyl cat's-eye1 or ,ceylon cat's-eye1 is found in various shadings of yellow1 brown1 and green1 and sometimes nearly black4 ,these stones are translucent to opaque1 and have a bright band of light running through the centre4 ,this band is nearly always white1 and in fine specimens is sharply defined1 not too wide1 and is in the centre of the stone4 ,the cat's-eye chrysoberyls are always cut convex or cabochon shape1 and as the stone is moved from side to side the band of light moves over its surface4 ,,cymophane4 ,the cymophane1 or floating light1 as the name denotes1 is a chrysoberyl with a bright spot of light which seems to float over the surface as the stone is moved4 ,the cymophane is also cut cabochon4 ,,alexandrite4 ,on the day that the ,emperor ,alexander of ,russia attained his majority the ,ural chrysoberyl1 of a dark-green color1 was found in the emerald mines of ,takowaja in the ,catherine ,mountains4 ,this wonderful stone is emerald-green to dark-green in color1 with often a slight red tint1 but by artificial light the green of good specimens changes to a beautiful columbine-red4 ,as the colors green and red are the national colors of ,russia1 and the date of discovery of this stone in ,russia occurred on the ,emperor's birthday1 the name alexandrite was given to this species of chrysoberyl4 ,the alexandrite is found in large pieces1 but is nearly always flawed and cracked4 ,this is a much-sought-after gem stone1 and specimens of from one to five carats command good prices4 ,up to the present time1 however1 good alexandrites have been rare1 and the demand has always exceeded the supply4 ,cat's-eyes and cymophanes are found in ,brazil in alluvial deposits of rivers1 and consequently in rolled and rubbed masses4 ,chrysoberyls are also found in ,russia1 ,germany1 ,america1 ,borneo1 ,pegu1 and ,moravia4 ,chrysolites and topazes are sometimes passed off for chrysoberyls4 ,the chrysolite is1 however1 lighter and softer1 while the topaz becomes electric from heating1 and is softer4 ,quartz cat's-eyes1 which are mistaken for chrysoberyl or ,oriental cat's-eyes1 have a specific gravity of about #b4fe1 hardness of #f to #f4e1 and are soluble in fluoric acid1 besides melting with soda into a clear glass4 ,they lack the bright1 hard polish of the chrysoberyl cat's-eye1 and there should be no difficulty in discovering the difference between the gem and the inferior stone4 ,,zircon4 ,the zircon1 hyacinth1 jacinth1 or jargoon belong to the tetragonal system of crystallization4 ,the cleavage is imperfect1 fracture conchoidal1 and specific gravity #d4d to #d4g1 the stone being much heavier than any other gems4 ,its hardness is #g4e and lustre vitreous to adamantine1 and refraction double to a high degree4 ,the zircon is phosphorescent when heated2 before the blow-pipe it is infusible1 but loses its color2 and with borax it melts into a transparent glass4 ,sulphuric acid affects this gem after long maceration4 ,the composition of the zircon is3 zirconia1 #ff4c2 silica1 #cc4g2 with a trace of peroxide of iron4 ,under the microscope1 the texture of these gems presents a watery appearance1 called by the ,french ratin1 and which looks like a liqueur poured into water4 ,this is a strong distinguishing point in the zircon4 ,the zircon1 hyacinth1 jargoon1 and jacinth are the same gems but of different colors4 ,the brown1 violet1 and green colors are known as zircons1 the red as hyacinth1 the yellow as jacinth1 and the grayish-white and white as jargoons4 ,the jargoon has often been palmed off as a diamond because of its transparent color and adamantine lustre4 ,the zircon is found in ,ceylon1 ,germany1 ,france1 ,bohemia1 ,america1 and in fact in nearly all parts of the earth1 as many as #abj localities having been noted where specimens of the mineral have been discovered4 ,the zircon can be distinguished from the garnet by its peculiar diamond-like brilliancy and its specific gravity4 ,,turquois4 ,the turquois is never found in crystals1 but in reniform or stalactitic masses4 ,the color varies from pea- and apple-green to greenish-blue1 sky-blue and dark-blue4 ,the hardness of the turquois is #f41 specific gravity #b4f to #b4h1 lustre waxy1 and condition opaque to slightly translucent4 ,before the reducing flame of the blow-pipe1 the turquois does not melt1 but becomes brown and colors the flame green4 ,with borax and salts of phosphorus the turquois melts to a clear glass1 while it is also soluble in hydrochloric acid4 ,oriental or mineral turquois is composed of3 ,alumina #dg4de ,phosphoric acid #bg4cd ,water #ah4ah ,oxide of copper #b4jb ,iron #a4aj ,oxide of manganese #j4ej ,phosphate of lime #c4da #ajj4jj ,the best color is a clear deep sky-blue1 and in the true turquois this color improves by artificial light2 imitation turquoises1 however1 lose their fine color under the same conditions4 ,the finest gem turquoises come from the northeastern part of ,persia1 between ,nishapoor and ,meshed4 ,here they are mined and partly cut1 and then the ,persian merchants carry them to ,russia1 where they are sold at the great annual fair of ,nijni-,novgorod and in ,moscow4 ,mineral turquoises are also found in ,new ,mexico1 ,arizona1 and ,nevada1 but not of sufficient size or sufficiently good color to make gem stones1 although they are prized for collections4 ,specimens are also found in ,burmah1 ,khorassan1 ,thibet1 ,china1 ,silesia1 ,saxony1 and on the ,isthmus of ,suez4 ,the stones from these places have1 as a rule1 but little value1 as the color fades or turns green from exposure to the light4 ,of late however1 some very good turquoises have come from ,egypt4 ,the color of a faded ,persian turquois can sometimes be restored by simply repolishing the stone4 ,occidental or bone turquoises called new rock or odontolites1 to distinguish them from the ,persian or old rock stones1 are of organic origin4 ,they are cut from the teeth of mammoths1 mastodons1 dinotheriums1 etc41 and are found near the town of ,simor1 in ,lower ,languedoc1 ,france4 ,these teeth1 the enamel of which is nearly as hard as the mineral turquois1 are colored by contact with phosphate of iron and copper1 which gives them a dark-blue1 light-blue1 and bluish-green color4 ,they are easily attacked by a file1 and totally destroyed by aqua-fortis4 ,when heated1 the fossil turquois or odontolite gives an offensive odor1 owing to the decomposition of animal matter4 ,the odontolite is lighter than the mineral turquois1 changes color by artificial light1 loses color in distilled water and alcohol1 and is translucent on the edges4 ,this fossil turquois does not fade like the mineral turquois1 but by artificial light appears of a dirty grayish-blue4 ,turquoises are sometimes artificially stained1 but this can be detected by applying a drop of ammonia to the back of the stone1 and if the color is artificial the ammonia will eat it off1 leaving a green spot4 ,ammonia does not affect the color of the ,persian turquois4 ,the so-called 8reconstructed0 turquoises are very close imitations of the real1 but are easily distinguished1 as they change rapidly to a deeper blue when immersed in water1 and while wet the surface of the stone shows cracks in every direction4 ,these stones become softer through soaking in water or alcohol4 ,the original color1 however1 returns when the stone is dry1 but the cracks remain in faint outline4 ,,tourmaline4 ,the tourmaline or precious schorl is known under many different names1 and no other mineral has such a suite of colors4 ,the colorless variety is known as achroite2 the red1 as rubellite or siberite2 the blue1 indicolite or ,brazilian sapphire2 the green1 ,brazilian emerald2 and the yellowish-green1 ,ceylon chrysolite or ,ceylon peridot4 ,besides the above colors and their shadings1 the tourmaline occurs in black and brown4 ,the crystallization is obtuse rhomboid1 and generally forms six-1 nine-1 and twelve-sided prisms4 ,some of the crystals are very large1 specimens over eight inches long having been mined4 ,the tourmaline crystals are remarkable for their varied and beautiful groupings of colors4 ,some are internally blue or brown1 surrounded by a bright carmine red or dull yellow2 others are red internally and are enveloped by a green exterior2 crystals are sometimes pink at the summit and light green at the base1 or crimson tipped with black1 or white at one end shading into green and finally into red at the other end4 ,the hardness of the tourmaline is #g to #g4e1 specific gravity #c to #c4a1 and lustre vitreous4 ,the tourmaline becomes decidedly electric by heating or rubbing1 and will readily attract small pieces of paper and other small objects4 ,the rubellite or red tourmaline is composed of3 ,silica #db4ac ,alumina #cf4dc ,boracic acid #e4gd ,oxide of manganese #f4cb ,lime #a4bj ,potash #b4da ,lithia #b4jd ,the green tourmaline is composed of ,silica #dj4 ,alumina #ci4af ,lithia and potash #c4ei ,protoxide of iron #e4if ,protoxide of manganese #b4ad ,boracic acid #d4ei ,volatile matter #a4eh ,the tourmaline possesses double refraction to a high degree1 and its power of polarizing light is so great that1 cut into slices1 it is used in the polariscope for analyzing other minerals4 ,if two slices of tourmaline1 cut parallel to their axis1 be laid one on the other in one direction1 both are transparent2 if laid in another direction they become opaque1 and if a doubly refracting crystal be placed between the two plates of tourmaline1 the part covered by the crystal is transparent while the other is opaque4 ,tourmaline melts with borax into a transparent glass2 the rubellite turns white1 and the indicolite and green tourmalines turn black1 under the blow-pipe4 ,tourmalines can be distinguished from other gems by their specific gravity1 but principally by their property of assuming polaric electricity after being heated1 one end becoming positive and the other negative4 ,the history of the discovery of the tourmaline and its electric property is a curious one4 ,on a warm summer day1 early in the eighteenth century1 some children were playing in a courtyard in ,amsterdam4 ,amongst their playthings were some precious stones which the ,dutch navigators had brought from ,ceylon4 ,some of the stones seemed to be possessed of the strange power of attracting and repelling small bits of straw1 ashes1 and other light substances4 ,the little ones called their parents to witness this strange phenomenon1 and the stolid ,dutch lapidaries1 themselves puzzled at the sight1 called the stones aschentreckers or ash-drawers4 ,a number of years afterwards1 careful experiments disclosed the wonderful electric powers of the aschentreckers or tourmalines4 ,purple1 green1 and blue tourmalines are found in ,brazil4 ,in ,ceylon the stones are found in gravel beds4 ,rubellites or siberites are found in ,siberia4 ,tourmalines are also found in ,moravia1 the island of ,elba1 ,sweden1 ,burmah1 ,tyrol1 ,canada1 and the ,united ,states4 ,the first tourmaline deposits known in the ,united ,states were discovered at ,paris1 ,maine1 in #ahbj4 ,another wonderful deposit was found at ,mt4 ,apatite in ,maine in #ahhb1 and up to the present time the finest tourmaline crystals have been discovered in the ,united ,states4 ,really fine specimens of red1 blue1 or green tourmalines are uncommon and command very good prices4 ,,opal4 ,the precious or noble opal1 fire opal1 common opal1 hydrophane1 and cachelong are different varieties of a mineral that is composed of about nine parts silica and one part water4 ,the colors vary from chalky-white to bluish-white1 from yellow to red1 and from a slight play of colors to the beautiful mingling of green1 blue1 and red with the most remarkable kaleidoscopic effects4 ,the opal is #e4e to #f in hardness1 specific gravity #b to #b4a1 lustre glassy1 and translucent from a slight to a very high degree4 ,the opal is found in an amorphous state and never crystallizes2 in fact from the condition of the pockets in which this mineral is found1 the indications are that the substance was once a fluid4 ,under the blow-pipe the opal loses its translucency and cracks but does not melt4 ,sulphuric acid will cause it to turn black1 and in a cold solution of caustic potash the opal is almost entirely soluble4 ,the precious or noble opal is found chiefly in the mines of ,czernowitza1 between ,kaschau and ,eperies1 in ,hungary1 and in ,gracias ,dios1 a province in ,honduras4 ,in olden times1 the ,greek and ,turkish merchants carried opals from ,hungary to the ,orient1 and then they were shipped to ,holland and sold in ,europe as ,oriental opals4 ,the fire opal is of a yellowish-red color1 and is found chiefly in ,mexico1 although it also occurs in ,hungary1 the ,faroe ,islands1 ,honduras1 and ,guatemala4 ,the common opal is found in ,ireland1 ,denmark1 ,frankfurt1 ,guatemala1 and ,south ,australia1 and also in ,hungary and ,mexico4 ,these opals are translucent without fire or reflection4 ,the hydrophane is an opal that has lost color and brilliancy by reason of the evaporation of its water4 ,if placed in water or alcohol1 this stone becomes transparent1 only to lose this quality when the water or alcohol has evaporated4 ,the hydrophane becomes transparent more quickly in warm than in cold water1 but most rapidly in alcohol4 ,if boiled in oil1 the hydrophane is said to retain its brilliancy for years4 ,the cachelong is milky-white1 and nearly opaque1 and is found in small masses in the river ,cach1 in ,bucharia1 and also in ,iceland4 ,although one of the most magnificent of the gem stones1 the opal for many years was under the ban of superstition4 ,now1 this splendid stone once more commands a foremost place in the jewelers' art1 and the opal mines of ,hungary and ,queensland are being worked to their fullest extent to supply the demand4 ,,pearl4 ,although an organic product1 the pearl is always ranked amongst the most precious of gems1 and is distinguished by being the only gem that does not require the lapidary's touch to bring out its beauties4 ,ancient writers have accounted for the origin of pearls by saying that they were formed of angels' tears1 or drops of dew from heaven1 which1 during the midsummer nights1 fell into the gaping mouths of the pearl-oysters4 ,according to modern scientific investigation1 the formation of the pearl does not seem to be the result of healthy natural causes1 but comes from the efforts of the oyster to rid itself of some foreign substance1 like a grain of sand1 a bit of shell or vegetation1 or some unwelcome visitor in the shape of a small water insect4 ,when annoyed by an intruding substance1 the oyster begins to deposit its nacre1 or mother-of-pearl1 in regular concentric layers around the intruder1 these layers gradually increasing in circumference and forming the pearl4 ,thus1 like an onion1 the pearl is merely a succession of layers or skins1 starting from a small core1 or nucleus1 which is always present1 though often only of microscopical size4 ,pearls have sometimes been found where the outer layer1 or skin1 as it is technically called1 has been discolored or otherwise injured1 and when this top skin has been carefully removed the result was a somewhat smaller but perfect pearl4 ,this1 however1 is a very delicate operation1 and at the pearling grounds is only resorted to by men of experience4 ,the composition of the pearl is carbonate of lime1 with a small proportion of organic matter1 and the specific gravity #b4e to #b4g4 ,the pearl is affected by acids1 and is easily calcined on exposure to heat4 ,in color1 the pure white1 slightly transparent1 is the most highly prized2 while in ,india and ,china the bright yellow colors are sought after4 ,decided colors1 however1 such as black1 pink1 and golden-yellow bring a high price1 and1 in fact1 black pearls1 if perfect in color and shape1 are at present more valuable than any other kind4 ,the beauty and value of a pearl depend on form1 quality of texture or skin1 color1 transparency or water1 and lustre or orient4 ,in form1 the perfectly round shape comes first in value1 then a finely formed drop or pear shape1 and lastly the oval or egg shape4 ,pearls that are flat on one side and rounded on the other are called boutons or button pearls4 ,these are frequently found attached to the shell1 and are cut out and the bottom part smoothed and polished4 ,it is easy1 however1 to detect this class of pearls by the lack of pearly lustre on the side that was attached to the shell4 ,when a pearl is rough and odd-shaped it is called a baroque1 and some extremely fantastic shapes are found1 especially in fresh-water oysters4 ,the texture or skin of a fine pearl should be perfectly smooth and free from all spots1 indentations1 wrinkles1 or scratches4 ,pure white is the desirable color for a gem pearl1 but many others that are slightly tinted with blue1 pink1 or yellow will pass for gems if they are otherwise perfect4 ,the transparency or 8water0 of a pearl1 while not existing in fact1 is still one of the requisites of a fine pearl2 there must be an appearance of transparency1 which adds to the beauty of the gem4 ,to describe the lustre or orient of the pearl1 the author can only use the term pearly1 as there is no other substance that approaches the brilliancy and color of a pearl1 excepting1 of course1 mother-of-pearl--the nacre in the pearl-oyster4 ,without orient or lustre1 the pearl of finest form and color has but little value4 ,lustre is to the pearl what brilliancy is to the diamond2 when the orient is absent there is no life1 no beauty4 ,pearls are principally supplied by two groups of pearl-oysters or mussels3 the marine or meleagrina margaritifera1 a round-cornered square shell with very thick sides1 measuring six to eight inches in length4 ,the color of this shell is mostly blackish-green1 but it is also sometimes yellowish2 the edges of the inner part of the shell are black1 but the rest of the interior is the beautiful mother-of-pearl4 ,the oyster itself is small for the size of the shell4 ,this specimen is found on the coast of ,ceylon1 ,persian ,gulf1 ,japanese1 ,mexican and ,california coasts1 the western shores of ,south ,america1 ,brazil1 ,west ,indian ,islands1 ,panama1 ,sooloo ,archipelago1 and the northeast and northwestern coast of ,australia4 ,the fresh-water or unio margaritifera is an even1 egg-shaped mussel found in brooks1 rivers1 and lakes in temperate zones in nearly all parts of the world4 ,some fine river pearls have been found in the ,united ,states1 but most of the ,american pearls are of a button or elongated shape1 or are baroques or fancy-shaped4 ,in ,china many people engage in the business of making small pellets of clay or metal images1 which in the month of ,may are introduced into the river mussels 7mytilus cygneus74 ,the mussels are replanted1 and in ,november they are taken up again4 ,some of the oysters die1 but most of them are found to have been actively at work covering the little pellets or metal figures with nacre1 and while no strictly first-class pearls are formed in this way1 many curious little pearl figures or gods are made and sold to the curious or devout4 ,pink or conch pearls are found in the ,gulf of ,california and coasts of ,mexico1 ,bahama ,islands1 ,west ,indian ,islands1 and in some rivers in ,south ,america4 ,they seldom occur in regular shapes1 and although they are termed pink pearls1 they range in color from red to pale yellow1 and are often found of a china-white color4 ,the pink pearl displays a wavy appearance and a peculiar sheen1 something like watered silk4 ,as the pink pearl is seldom found perfectly round and of a good color1 such a specimen is very valuable4 ,,chrysolite4 ,the chrysolite1 peridot1 and olivine differ in color1 but are practically of the same composition4 ,the chrysolite proper is of a pale greenish-yellow color1 the peridot a deep olive-green1 and the olivine of a yellowish or light olive-green color2 these stones also shade into brown4 ,they crystallize on the rhombic system1 are transparent to translucent1 #f4e to #g4 in the scale of hardness1 and #c4c to #c4e in specific gravity4 ,the cleavage is distinct1 fracture conchoidal1 refraction double1 and lustre vitreous1 and in the olivines somewhat greasy4 ,these stones are easily affected by sulphuric acid1 but are infusible before the blow-pipe1 excepting some kinds containing much iron4 ,with borax1 they melt to a pale-green transparent glass4 ,chrysolites are composed of silica1 magnesia1 and oxide of iron4 ,perfectly crystallized chrysolites are brought from ,constantinople1 but the exact locality where they are found is unknown4 ,less distinct specimens occur at ,vesuvius1 ,mexico1 the isle of ,bourbon1 ,auvergne1 ,egypt1 ,natolia1 ,brazil1 ,germany1 ,pegu1 ,ceylon1 ,switzerland1 and ,north ,america4 ,peridots are distinguished by being the only precious stones that have literally dropped from heaven1 as they have been found in meteorites4 ,the ,oriental chrysolite of commerce is true chrysoberyl1 and is harder and heavier than chrysolite1 and the stone called ,ceylon chrysolite is a greenish-yellow tourmaline1 which is easily distinguished1 as it is also harder while considerably lighter than the chrysolite4 ,the green garnet is of a pronounced green color1 and is harder and heavier than the olivine or chrysolite4 ,although suitable for mounting in brooches and other ornaments1 these stones are not sufficiently hard for the rough usage as ring-stones4 ,,garnet4 ,almandine1 almandite1 ,syrian garnet1 essonite1 cinnamon-stone1 pyrope1 ,bohemian garnet1 vermeille1 ,cape garnet1 ,cape ruby1 ,arizona ruby1 ,american ruby1 carbuncle1 uwarowite1 demantoide1 grossularite1 and ,bobrowska garnet are some of the scientific and commercial names for different species and colors of the garnet group4 ,the crystallization of the garnet is isometric1 refraction single1 specific gravity #c4ae to #d4c1 hardness #e to #h1 lustre vitreous1 fracture uneven1 colors red1 violet1 brown1 yellow1 green1 and white1 and the various shadings of these colors4 ,most varieties fuse easily to a brown or black glass2 the uwarowite fuses with borax to a clear chrome-green glass4 ,syrian1 almandine1 almandite1 and carbuncle are different names for the iron-alumina garnet4 ,in colors1 these stones shade from deep-red to violet and brownish-red1 and are composed of3 ,silica #cf4ja ,alumina #bj4jf ,protoxide of iron #dc4jc ,the specific gravity is #d4 to #d4b1 and hardness #g4e4 ,this garnet1 sometimes called the precious garnet1 is found in ,ceylon1 ,pegu1 ,brazil1 ,greenland1 ,hindustan1 ,bohemia1 ,tyrol1 tzthal1 ,carinthia1 ,styria1 ,switzerland1 ,ariolo1 ,canaria1 ,maggia1 ,hungary1 ,sweden1 ,norway1 ,scotland1 ,spain1 and the ,united ,states4 ,grossularite1 or lime-alumina garnet1 is known in commerce as essonite1 or cinnamon-stone4 ,the color is yellow1 of various shades2 specific gravity #c4e to #c4fe1 and hardness #f4e4 ,these stones are sometimes sold for jacinths1 but they are softer than the jacinth1 and melt easily before the blow-pipe4 ,essonites come principally from ,ceylon1 but are also found in other places4 ,pyrope or ,bohemian garnet is the magnesia-alumina variety1 and is of a uniform dark blood-red color4 ,this stone is found in ,bohemia1 and although quantities of small pieces are found1 large specimens are rare1 and a piece that will cut into a four- or five-carat stone is seldom met with and commands a high price4 ,these garnets are found at ,stiefelburg by ,meronitz1 ,triblitz1 ,podsedlitz1 and ,neupaka4 ,the pyrope turns black under the blow-pipe1 then red again1 and melts with difficulty into a black glass4 ,with borax it melts to an emerald-green glass4 ,the specific gravity of this garnet is #c4fi to #c4gh1 and hardness #g4e4 ,vermeille is a name given to the orange-red almandine1 ,cape garnet to the bright red-yellow variety1 ,cape ruby to the pyrope1 and ,american ruby to the blood-red kind found in ,new ,mexico1 ,montana1 and ,arizona4 ,carbuncle is a term applied to all garnets cut with a smooth rounding top1 sometimes called1 after the ,french1 cabochon4 ,uwarowite or lime-chrome garnet is one of the rarest and most beautiful of the garnet group4 ,the color of this stone is emerald-green1 hardness #g4e1 and specific gravity #c4da to #c4eb4 ,uwarowites are found near ,bissersk in the ,urals of ,russia1 but rarely in specimens of sufficient size to cut into gems4 ,this garnet is heavier and harder than the true emerald4 ,demantoide or ,bobrowska garnet is a soft garnet1 olive-green to brown and blackish-green in color1 sometimes light green4 ,it is found in the ,bobrowska ,river in the ,urals4 ,the specific gravity is #c4he1 and hardness about #f1 its softness making it undesirable for many ornaments4 ,before the blow-pipe it fuses into a black bead4 ,these garnets are often sold as olivines2 they are heavier than olivines and softer4 ,demantoide is composed of3 ,silica #ce4dd ,lime #cb4he ,sesquioxide of iron #cb4he ,magnesia 4#bj ,,topaz4 ,topaz belongs to the rhombic system of crystallization4 ,its cleavage is basal and perfect1 fracture uneven1 hardness #h1 scratching quartz distinctly1 specific gravity #c4d to #c4f1 lustre vitreous1 refraction double1 and colors ranging from colorless or white to bluish-white1 light blue1 wine-yellow1 straw-yellow1 golden-yellow1 greenish- and pale-red to pink4 ,topaz becomes electric from rubbing or pressure1 and retains electricity for twenty-four hours4 ,before the blow-pipe topaz partly loses color1 but does not melt1 and with borax it fuses slowly to a white bead4 ,topaz is partially attacked by sulphuric acid1 and dissolves in salts of phosphorus4 ,the composition of topaz is3 ,silicon #ae4je ,aluminium #cj4jb ,oxygen #cf4jh ,fluorine #ag4je ,goutte d'eau or colorless topaz1 sometimes called 8slaves diamond10 ,siberian or bluish-white1 ,brazilian or golden to reddish-yellow1 ,saxony or pale-wine yellow1 ,brazilian ruby or pink1 ,brazilian sapphire or light blue1 and aquamarine or greenish1 are the various commercial names for topaz4 ,most of the ,brazilian rubies or pink topazes are produced by heating the reddish or dark-yellow variety1 either in a crucible or by enveloping the stone in ,german tinder and setting fire to the tinder4 ,if heated too much1 the stone is apt to become colorless1 and if suddenly cooled it may crack4 ,colorless or white topaz takes a very high polish1 and is wonderfully clear and transparent4 ,the great ,portuguese diamond1 8,the ,braganza10 of about #a1fhj carats1 is supposed to be a white topaz4 ,topaz is found in the ,urals1 ,kamschatka1 ,alabaschka1 ,miask1 ,nestschinsk1 ,adun ,tschilon1 ,villa ,rica1 ,boa ,vista1 ,capao1 ,lana1 ,minas ,novas1 ,cairngorm ,mts41 ,schlackenwald1 ,zinnwald1 ,schneckenstein1 ,ehrenfriedensdorf1 ,altenburg1 ,orenburg1 ,mourne ,mts4--,ireland1 ,australia1 ,new ,south ,wales1 ,ceylon1 ,mexico1 and the ,united ,states4 ,false topaz1 or the ordinary topaz of commerce1 is yellow quartz resembling yellow topaz1 but lacking its brilliancy and hardness2 it is also very much lighter1 being only #b4e to #b4g in specific gravity4 ,beryl and chrysolite are often mistaken for topaz1 but as they are softer and beryl is much lighter1 they are easily distinguished from the topaz4 ,the strong electric property of the topaz is also a conclusive test4 ,oriental topaz1 or yellow corundum1 is harder and heavier than the occidental or true topaz4 ,,apatite4 ,apatite1 which is seldom used as a gem stone1 sometimes resembles the beryl and emerald1 but is much softer and rarely has the color and brightness combined of the former gems4 ,this mineral1 composed principally of subsesquiphosphate of lime1 is #d4e to #e4 in hardness1 has the specific gravity of #b4ie to #c4be1 is transparent to opaque1 vitreous in lustre1 infusible before the blow-pipe1 and dissolves slowly in nitric acid4 ,in colors1 apatite varies from colorless to sea-green1 bluish-green1 violet-blue1 gray1 yellow1 red1 and brown4 ,apatite is found in ,saxony1 the ,hartz ,mts41 ,bohemia1 ,norway1 ,bavaria1 ,england1 ,st4 ,gothard in ,switzerland1 and in the ,united ,states4 ,,felspar4 ,four varieties of felspar are used as gem stones--moonstone or orthoclase1 sunstone or avanturine felspar1 ,amazon stone or green felspar1 and ,labrador or ,labrador spar4 ,,moonstone4 ,this variety of felspar is called orthoclase1 adularia1 and orthose1 besides the commercial names of fish-eye1 ,ceylon or water opal1 and in the yellow and red tints sunstone4 ,moonstone occurs in crystals and crystalline fragments1 also massive and granular2 its hardness is #f4 to #f4e1 specific gravity #b4d to #b4f1 refraction double1 is not attacked by acids1 and is composed of3 ,silica #fd4e ,alumina #ah4e ,potash #ag4 ,with traces of soda4 ,this beautiful stone is the clearest of all varieties of felspar4 ,it is colorless1 or only slightly tinted with blue1 green1 yellow1 and flesh-red1 and is transparent to translucent4 ,the lustre is vitreous1 and a brilliant pearly streak of white light plays from side to side4 ,the yellowish- and reddish-tinted specimens are called sunstones1 and are quite rare4 ,these sunstones must not be confounded with the avanturine or felspar sunstone4 ,moonstones are found principally in ,ceylon and on the ,st4 ,gothard in ,switzerland1 but also occur in ,bavaria1 ,greenland1 ,tyrol1 ,dauphine1 ,norway1 and the ,united ,states4 ,during the past few years1 large quantities of moonstone balls1 cut like whole pearls1 have been used for jewelry--the stones being much sought as well because of their beauty as on the ground of the popular superstition that they will bring good luck to the wearer4 ,small pieces or balls are not very valuable1 but large perfect specimens command a good price4 ,,sunstone4 7,,avanturine ,,felspar47 ,sunstone or avanturine felspar is a variety of oligoclase2 grayish-white to reddish-gray in color1 usually the latter2 containing minute crystals of hematite1 gthite or mica1 which are imbedded and scattered through the stone1 and give forth golden-yellow1 reddish1 or prismatic reflections4 ,the hardness is #f to #g1 specific gravity #b4ef to #b4gb1 and lustre pearly or waxy to vitreous4 ,sunstones are found near ,stockholm1 in ,finland1 the ,urals1 ,ceylon1 the ,alps1 ,iceland1 the ,united ,states1 and other places4 ,,amazon ,,stone4 7,,green ,,felspar47 ,the ,amazon stone is a green variety of felspar1 which was first found on the banks of the ,amazon ,river1 but now comes from ,siberia and the ,united ,states4 ,this stone consists of potash1 alumina1 and silex--is green in color but rarely clean1 being discolored in places and usually covered with small white spots4 ,the ,amazon stone is harder than glass1 but is scratched by rock crystal4 ,its specific gravity is #b4e to #b4f2 acids do not affect it1 and it melts with difficulty before the blow-pipe4 ,,labradorite4 ,labrador stone or labradorite is sometimes known as opaline felspar1 and was first discovered on the island of ,st4 ,paul on the coast of ,labrador4 ,labradorite is translucent to opaque1 gray-green or brown in color1 and has beautiful chatoyant reflections of brilliant blue1 sea-green1 and sometimes red and yellow1 changing from one color to another4 ,labradorite is #f in hardness1 has a specific gravity of #b4fb to #b4gf2 a vitreous to pearly lustre1 is brittle1 fuses with difficulty before the blow-pipe1 and is decomposed by muriatic acid4 ,it is composed of3 ,silica #eb4i ,alumina #cj4c ,lime #ab4c ,soda #d4e ,large masses of this stone are found on the coast of ,labrador4 ,it is also found in ,finland1 ,russia1 and the ,united ,states4 ,because of the dark chatoyant appearance the name of il de buf or ox-eye is sometimes applied to labradorite4 ,handsome specimens1 cut cabochon1 form pretty ring stones1 and many effective engraved cameos have been produced by using the bright portion for the relief work and the gray dead part for the base4 ,,cyanite4 ,this stone is the transparent variety of disthene1 and is sometimes commercially known as sappare4 ,cyanite is colorless to bluish-white1 sky-blue1 berlin blue1 yellowish- and reddish-white1 gray1 and green4 ,the hardness is #e to #g1 specific gravity #c4de to #c4gj1 lustre vitreous and pearly2 it is infusible before the blow-pipe1 but fuses with borax2 is not attacked by acids1 and is composed of3 ,silica #cf4h ,alumina #fc4b ,cyanite is found in ,switzerland1 the ,tyrol1 ,styria1 ,carinthia1 ,bohemia1 ,norway1 ,finland1 ,france1 ,south ,america1 ,scotland1 ,ireland1 ,siberia1 the ,east ,indies1 and the ,united ,states4 ,clean specimens are not plentiful1 and fine blue pieces have frequently been sold for sapphires4 ,the cyanite can be distinguished from the sapphire by its inferior hardness and lighter weight4 ,,lapis ,,lazuli4 ,lapis lazuli1 the sapphire of the ancients1 is a mineral1 translucent to opaque1 ranging in color from colorless to an azure-blue1 violet-blue1 green1 and red4 ,the principal color1 however1 is a rich1 azure blue1 sometimes shading into green1 and having a vitreous to greasy lustre4 ,its hardness is #e to #e4e1 specific gravity #b4ch to #b4db2 it is decomposed by muriatic acid1 and fuses before the blow-pipe to a white glass4 ,it is rarely found clean1 but has usually a number of veins and spots of a metallic nature4 ,it is composed of3 ,silica #de4 ,alumina #ca4gf ,soda #i4ji ,lime #c4eb ,sulphuric acid #e4hi and traces of iron1 soda1 and potash4 ,this mineral is found in ,siberia1 ,transylvania1 ,persia1 ,china1 ,thibet1 ,tartary1 ,south ,america1 ,india1 and ,brazil4 ,lapis lazuli is sometimes employed for jewelry1 and was for some centuries ground up and used to make the mineral paint known as genuine ultramarine4 ,this paint is now produced chemically1 and the more costly mineral compound is rarely used4 ,the imitation of lapis lazuli for jewelry purposes is also very easy1 as metal filings can be readily introduced into the azure blue glass1 and thus an imitation of the genuine stone produced1 which is perfect excepting in hardness4 ,,hiddenite4 ,the hiddenite is a variety of spodumene that has only been found in one locality1 namely1 ,alexander ,county1 ,north ,carolina4 ,this mineral was discovered by ,w4 ,e4 ,hidden1 and has been named after him4 ,the hiddenite is perfectly transparent1 and varies from a pale yellowish- to a deep emerald-green1 being very brilliant1 and approaching the emerald in color4 ,as this stone is rarely found large enough for cutting into gems1 it is highly prized1 and good specimens command a large price4 ,the hardness of the hiddenite is #f4e to #g1 and specific gravity #c4ac to #c4ai2 before the blow-pipe it melts to a clear glass1 and it is attacked by salts of phosphorus4 ,it is composed of3 ,silica #fd4ce ,alumina #bf4eh ,lithia #g4je with traces of iron and soda4 ,,spodumene4 ,spodumene is sometimes cut and polished as a gem1 but its peculiar cleavage makes it a bad stone for the lapidary to cut and the jeweler to mount4 ,its hardness is #f4e to #g1 specific gravity #c4ac to #c4ai1 and lustre1 vitreous to pearly4 ,grayish-green1 greenish-white1 and sometimes yellow or faint red are the colors4 ,its composition is3 ,silica #fd4b ,alumina #bi4d ,lithia #f4d ,acids do not attack spodumene1 and under the blow-pipe it fuses to a white glass4 ,this mineral is found in ,sweden1 the ,tyrol1 ,ireland1 ,scotland1 and the ,united ,states4 ,,dichroite4 ,dichroite is sometimes known under the mineralogical names of cordierite and iolite1 and commercially as saphir d'eau1 or water sapphire4 ,this stone is remarkable for pleichroism1 sometimes showing three different colors in as many directions1 and when properly cut has often the star formation of the corundum star-stones4 ,water sapphire1 as the blue specimens are called1 is #g to #g4e in hardness1 specific gravity #b4ef to #b4fg1 transparent to translucent1 and frequently full of flaws4 ,it is partially decomposed by acids1 melts with difficulty before the blow-pipe1 is vitreous to greasy in lustre1 and is composed of3 ,silica #di4 ,alumina #cb4 ,ferrous oxide #g4 ,magnesia #i4 ,besides the saphir d'eau1 which is blue1 dichroite occurs colorless1 bluish-white1 yellowish-white1 yellowish-gray to yellowish-brown1 indigo to blackish-blue1 and violet4 ,this mineral is found in ,ceylon1 ,spain1 ,norway1 ,sweden1 ,tuscany1 ,greenland1 and ,bavaria4 ,sapphire is harder and much heavier than dichroite4 ,,idocrase4 ,idocrase or vesuvianite was first found amongst the ancient ejections of ,vesuvius1 and it is still found at ,vesuvius in hair-brown to olive-green colors4 ,vesuvianite is #f4e in hardness1 #c4ce to #c4de in specific gravity1 transparent to opaque1 lustre vitreous to greasy4 ,it possesses strong double refraction1 is attacked by acids1 and melts readily under the blow-pipe4 ,vesuvianite consists of3 ,silica #cg4ge ,alumina #ag4bc ,sesquioxide of iron #d4dc ,magnesia #c4gi ,lime #cg4ce ,in colors1 this mineral shades from brown to black1 yellow1 pale-blue1 and green1 and it is found at ,vesuvius1 ,alps1 ,piedmont1 ,mt4 ,somma1 ,etna1 ,norway1 ,sweden1 ,spain1 ,hungary1 ,urals1 and the ,united ,states4 ,transparent or strongly translucent specimens1 in handsome green or brown varieties1 are used for jewelry1 principally1 however1 in ,turin and ,naples4 ,chrysolite and green garnet are sometimes substituted for vesuvianite4 ,the first has a greater specific gravity and is more vivid in color1 and the latter is also heavier and harder4 ,,euclase4 ,euclase is very brittle1 and therefore is rarely used as an ornamental stone4 ,this mineral has the hardness of #g4e2 specific gravity1 #c4a2 lustre1 vitreous to pearly2 it is transparent to semi-transparent1 doubly refractive1 is not acted upon by acids1 fuses under the blow-pipe to a white enamel1 and is composed of3 ,silica #da4b ,alumina #ce4b ,glucina #ag4d ,water #f4b ,euclase occurs in ,brazil1 in the neighborhood of ,villa ,rica1 and also in the ,urals1 in colorless1 pale green1 blue1 pale yellow1 and white colors4 ,,sphene4 ,sphene or titanite is also a brittle mineral1 #e to #e4e in hardness2 specific gravity1 #c4d to #c4ef2 transparent1 doubly refractive2 lustre1 adamantine to resinous2 colors1 brown1 gray1 yellow1 green1 black1 and colorless2 and composition3 ,silica #ca ,titanium oxide #da ,lime #bg ,ferrous oxide #a ,when transparent in colorless1 greenish1 or yellow colors1 this mineral presents an appearance like the fire opal4 ,sphene is found in ,switzerland1 the ,urals1 ,tyrol1 ,finland1 ,wales1 ,ireland1 ,germany1 ,canada1 and the ,united ,states4 ,,phenacite4 ,this mineral1 rarely used as a gem stone1 is #g4e to #h in hardness2 specific gravity1 #b4if to #c2 lustre1 vitreous2 transparent to semi-translucent1 doubly refractive1 it does not melt before the blow-pipe1 and contains3 ,silica #ed4b ,glucina #de4h ,phenacite occurs colorless1 and also bright wine-yellow inclining to red1 and brown4 ,this stone is found in ,russia1 ,mexico1 and ,alsace4 ,the colorless or transparent variety approaches the diamond in brilliancy1 especially under artificial light4 ,,epidote4 ,epidote usually occurs in a peculiar yellowish-green1 called pistachio green1 a color that is seldom found in other minerals4 ,besides this color1 olive1 brownish-green1 greenish-black and black1 red1 yellow-gray1 and grayish-white occur4 ,the hardness of epidote is #f to #g2 specific gravity1 #c4cb to #c4ej2 lustre1 vitreous to pearly2 refraction1 double4 ,the stone is transparent to opaque1 is attacked by acids1 and is slightly affected by the blow-pipe4 ,it is composed of3 ,silica #ch ,alumina #bb ,ferric oxide #ae ,lime #bc ,water #b ,epidote is found in ,norway1 ,saxony1 ,siberia1 ,brazil1 on the ,st4 ,gothard1 in ,switzerland1 in the ,tyrol1 and in the ,hartz4 ,,axinite4 ,axinite is a brittle mineral which has occasionally furnished some pretty gem stones4 ,the hardness of this stone is #f4e to #g2 specific gravity1 #c4 to #c4c2 lustre1 vitreous4 ,it is transparent to translucent1 is not attacked by acids1 and melts readily before blow-pipe4 ,it is composed of3 ,silica #dc ,lime #bj ,alumina #af ,ferric oxide #aj ,boron trioxide #e ,manganese dioxide #c ,magnesia #b ,potash #a ,axinite occurs in clove-brown1 plum-blue1 and pearl-gray1 and exhibits trichroism4 ,the best specimens come from ,st4 ,christophe in ,dauphiny1 but it is also found at ,santa ,maria1 and in ,switzerland1 ,sweden1 ,england1 ,chili1 ,saxony1 the ,hartz ,mountains1 and the ,united ,states4 ,axinite is usually cut1 like the opal1 cabochon1 but is rarely used as a gem stone4 ,,diopside4 ,diopside is cut and sometimes sold in ,turin and in ,chamouny as a gem stone1 but no great quantity of this mineral is used for ornamental purposes4 ,the hardness of diopside is #e to #f2 specific gravity1 #b4i to #c4e2 lustre1 vitreous to greasy4 ,it is transparent to translucent1 brittle1 cannot be dissolved by acids1 and melts before the blow-pipe4 ,it is composed of3 ,silica #ed ,lime #bd ,magnesia #ah ,ferrous oxide #d ,this mineral is grayish-white to pearl-gray1 and greenish-white to greenish-gray4 ,the best green transparent specimens are from the ,mussa ,alp and ,zillerthal1 but it is also found in the ,urals and the ,united ,states4 ,,fluor ,,spar4 ,this mineral occurs in many colors1 often approaching the finer gems in appearance1 and bearing the commercial names of false ruby1 false emerald1 false topaz1 etc41 etc41 according to its color4 ,fluor spar is brittle1 #d in hardness1 has the specific gravity of #c4a to #c4b1 single refraction1 is transparent to translucent1 has a vitreous lustre1 phosphoresces when heated1 is attacked by acids1 and melts before the blow-pipe4 ,it is composed of3 ,fluorine #dh4g ,calcium #ea4c ,white1 yellow1 green1 rose- and crimson-red1 violet-blue1 sky-blue1 and brown1 wine-yellow1 greenish-blue1 and gray are the colors of this many-tinted mineral4 ,fluor spar is found in ,england1 ,norway1 ,baden1 ,nova ,scotia1 ,thuringia1 the ,alps1 ,saxony1 and the ,united ,states4 ,large pieces of this mineral are made into beautiful vases and ornaments4 ,,hypersthene4 ,handsome specimens of hypersthene or ,labrador hornblende are used for ornamental purposes4 ,this mineral is found in crystalline masses1 has the hardness of #f1 specific gravity #c4c to #c4d1 lustre pearly to metallic4 ,it is translucent to opaque1 brittle1 and fuses before the blow-pipe4 ,it consists of3 ,silica #ed4b ,magnesia #bd4a ,protoxide of iron #ba4g ,hypersthene occurs in dark-brown1 green1 grayish-black1 greenish-black1 and jet-black colors1 and is found in the isle of ,skye1 the ,hartz ,mountains1 ,saxony1 ,labrador1 ,greenland1 ,norway1 ,sweden1 ,bohemia1 ,thuringia1 and the ,united ,states4 ,,quartz4 ,the quartz group is the largest and most diversified among precious stones4 ,quartz occurs massive1 in concretions1 and in confused crystalline masses4 ,on account of the abundance of the massive kinds1 such as jasper1 agates1 onyx1 etc41 some writers place the quartz group under the head of semi-precious stones1 and lately the ,united ,states customs authorities have gone further in that direction1 and have ruled that 8because of the abundance and comparative cheapness of agates1 onyxes1 etc41 they were no longer precious stones40 ,this position1 however1 the custom-house speedily abandoned1 and1 for dutiable purposes at least1 the quartz family1 in all its ramifications1 is recognized as belonging to the precious stones4 ,harder than the tourmaline1 turquois1 or opal1 as hard as the chrysolite1 and nearly as hard as the garnet or emerald1 there is no reason why the crystallized varieties1 such as amethyst1 cairngorm1 false topaz1 chrysoprase1 and even the cat's-eye and finer onyxes1 should not be classed among the precious stones4 ,some more plentiful and less beautiful varieties of quartz are not valuable1 and they take the same position in the quartz family that the huge imperfect crystals do in the beryl group4 ,whenever the specimen is sufficiently beautiful to be cut and polished for setting in jewelry1 it should be included under the precious stones4 ,quartz crystallizes in the rhombohedral system1 and many varieties are found massive and compact4 ,the cleavage is indistinct but can sometimes be found by plunging a heated crystal into cold water4 ,the hardness of quartz is #g2 specific gravity #b4e to #b4h1 the purest kinds being #b4fe2 the lustre is vitreous to resinous1 and fracture conchoidal4 ,quartz is tough1 brittle1 and feels cold2 it becomes positively electric by rubbing1 shows phosphorescence in the dark1 and gives sparks if struck with another piece of quartz or with steel4 ,quartz is transparent to translucent1 semi-translucent to opaque1 doubly refractive1 and does not melt before the ordinary blow-pipe1 but may be melted with the oxyhydrogen blow-pipe4 ,it also melts with soda to a clear glass1 and is soluble in fluohydric acid4 ,quartz is composed of pure silica ,oxygen #ec ,silicon #dg ,some of the impure varieties contain oxide of iron1 carbonate of lime1 clay1 and other minerals4 ,,crystallized ,,quartz4 ,colorless quartz or pure rock-crystal is found in many parts of the world1 notably in ,switzerland1 ,dauphiny1 ,piedmont1 the ,carrara quarries in ,italy1 ,canada2 in ,herkimer ,county1 ,new ,york1 and on the shores of ,lake ,george1 in the same place2 at ,hot ,springs1 ,arkansas2 and along the beach of ,long ,branch1 ,cape ,may1 and many other places4 ,rock-crystal1 commercially known as ,bohemian diamond1 occidental diamond1 ,lake ,george diamond1 rhinestone1 pebble1 etc41 etc41 is colorless and transparent4 ,this stone is largely used for optical purposes1 and is also sometimes cut into brilliants to imitate the diamond4 ,while rock-crystal is considerably harder than strass or paste1 it lacks1 however1 the brilliancy of the fine-composition imitation diamond4 ,besides being much softer1 the paste is often heavier than the crystal1 because of the quantity of lead and other minerals used in its composition4 ,,amethyst4 ,amethystine quartz or amethyst varies in color from light to clear-dark purple1 sometimes nearly black1 and from light to dark bluish-violet4 ,the coloring of the stone is supposed to be due to manganese4 ,the best amethysts come from ,brazil and ,ceylon1 but good specimens are found in ,india1 ,persia1 ,botany ,bay1 ,transylvania1 near ,cork and the island of ,may in ,ireland1 at ,oberstein1 in ,saxony1 in ,hungary1 ,siberia1 ,nova ,scotia1 ,sweden1 ,bohemia1 ,canada1 and in the ,states of ,maine1 ,pennsylvania1 ,colorado1 ,georgia1 ,virginia1 and ,michigan4 ,under heat1 the amethyst turns first yellow1 then green1 and finally becomes colorless4 ,the value of an amethyst depends upon the fashion1 and the time has been when these stones ranked among the most valuable of precious stones4 ,at present1 a fine amethyst can be bought for very little money1 but should the stone become fashionable again1 the best specimens will command good prices4 ,,yellow ,,quartz4 ,yellow quartz1 known as false topaz1 ,bohemian1 occidental1 ,indian1 or ,spanish topaz1 resembles the real topaz in color1 but is softer1 lighter1 different in crystallization and cleavage1 and in electrical properties4 ,in color1 this stone varies from the lightest yellow to orange-red and brown4 ,most of the yellow quartz comes from ,brazil1 and much of it is changed to yellow by burning amethyst and smoky quartz4 ,,cairngorm1 ,,etc4 ,smoky yellow to smoky brown1 often gray and black1 are the tints of the cairngorm4 ,this species of transparent quartz takes its name from ,cairngorm in ,invernessshire1 in ,scotland1 a locality where some of the best specimens have been found4 ,pike's ,peak1 ,arkansas1 and certain districts in ,north ,carolina have also produced some very fine smoky topazes4 ,the cairngorm is used for seals1 beads1 and some of the cheaper jewels1 and is largely sold at watering-places in ,switzerland1 and in the ,western ,united ,states4 ,the stone is very popular in ,scotland4 ,hair or needle stones is the name given to these varieties of crystallized quartz when they contain foreign substances1 such as rutile1 manganese1 chlorite1 etc41 in hair or needle formation4 ,these stones are cut to represent the needle enclosures in an upright position1 and are called sagenite or ,venus hair stones or love arrows4 ,iridescent or rainbow quartz is the variety of rock-crystal containing cracks and fissures which reflect all the colors of the rainbow4 ,quartz can also be artificially colored by rapidly cooling a heated specimen and then dipping the piece into a coloring preparation2 the minute cracks in the quartz absorb the coloring matter1 and the result is a red-1 blue-1 or green-tinted stone4 ,the massive varieties of quartz embrace the rose quartz1 avanturine1 cat's-eye1 crocidolite1 heliotrope1 chrysoprase1 prase1 plasma1 chalcedony1 agates1 onyx1 carnelian1 jasper1 hornstone1 and flint4 ,,rose ,,quartz4 ,rose quartz occurs in a massive form1 usually very imperfect and cracked1 and varying in color from rose-red to pink4 ,the color is supposed to be due to titanic acid1 and often becomes paler on exposure4 ,this stone is nearly opaque and semi-transparent on the edges1 has a greasy lustre1 and specific gravity of #b4fe to #b4ge4 ,rabenstein near ,zwiesel in ,bavaria1 the ,united ,states1 ,brazil1 ,france1 ,ceylon1 ,finland1 and ,siberia are places where rose quartz has been found4 ,,avanturine4 ,avanturine is an opaque1 yellow1 brown1 or red quartz1 spangled with minute scales of mica or some other mineral1 and found principally near ,madrid1 in ,spain4 ,it is also found in ,france1 ,scotland1 ,bavaria1 the ,urals1 and ,styria4 ,a beautiful imitation of avanturine1 called goldstone1 is manufactured of glass into which metal filings are introduced4 ,this goldstone is superior to avanturine in every point except that of hardness4 ,avanturine and its imitation1 but largely the latter1 are used for the cheaper kinds of jewelry1 and were very popular in the ,united ,states some years ago4 ,,cat',s-,,eye4 ,the ,hungarian1 occidental1 or quartz cat's-eye is found on the coast of ,malabar1 ,ceylon1 ,hartz ,mountains1 and ,bavaria4 ,this stone is translucent to opaque1 gray1 green1 brown1 red1 and the shadings of these colors1 but usually a greenish-gray1 with a mass of fine white lines in the centre1 which give to the stone a chatoyant appearance4 ,the cat's-eye is usually cut cabochon or carbuncle-shaped1 and the lines 7which are due to the fibres of asbestos7 are kept in the centre of the stone1 and play like the eye of a cat when the stone is moved4 ,the quartz cat's-eye is easily distinguished from the oriental of chrysoberyl cat's-eye1 as it is softer and much lighter4 ,,crocidolite4 ,crocidolite or tiger-eye is a light-brown1 brownish-yellow to dark-green1 and greenish-blue quartz1 which has the same chatoyant qualities as the cat's-eye4 ,when cut cabochon1 the crocidolite is called tiger-eye4 ,this beautiful mineral was very rare some years ago1 and good specimens were sold by the carat4 ,great quantities1 however1 have lately been found in ,south ,africa1 and although the finest pieces are still used for cameos and intaglios1 many objects1 such as paperweights1 umbrella handles1 match-safes1 etc41 are now cut from this stone4 ,crocidolite is often artificially colored to very closely imitate some of the finest shades of the oriental cat's-eye4 ,,heliotrope4 ,heliotrope or blood-stone1 as this variety is commonly called1 is a dark-green quartz1 translucent to opaque1 and covered with small red spots or blood-colored blotches1 from which the stone derives the name of blood-stone4 ,this stone has long been used for seal and signet purposes1 and many fine intaglios and cameos carved in blood-stone are in existence4 ,bucharia1 ,tartary1 ,siberia1 ,east ,india1 ,china1 the island of ,rum in the ,hebrides1 the ,united ,states1 and ,canada are some of the places where the heliotrope is found4 ,,chrysoprase4 ,the chrysoprase is an apple-green chalcedony1 sometimes olive- or whitish-green4 ,it is translucent1 scratches glass1 and has the specific gravity of #b4ef4 ,the color is due to the presence of oxide of nickel4 ,this stone is found principally in ,silesia1 but also in ,siberia and the ,united ,states4 ,large pieces of chrysoprase are rare1 and even the best specimens lose their color in course of time4 ,,prase4 ,a translucent1 spotted leek-green1 green quartz1 which loses its polish on exposure to the air1 is known as prase4 ,this stone is found principally in the iron mines of ,brietenbaum1 ,saxony1 and also in ,brittany1 the ,tyrol1 ,scotland1 ,salzburg1 ,finland1 and the ,united ,states4 ,prase is sometimes known commercially as 8mother of emerald10 and a greenish crystalline quartz is also often called prase4 ,,plasma4 ,plasma is a dark grass-green quartz1 feebly translucent1 and is sometimes covered with white or yellow spots4 ,plasma is somewhat lighter in weight than the heliotrope and does not take as fine a polish4 ,this stone is found in ,india1 ,china1 and in the ,black ,forest1 ,germany4 ,,chalcedony4 ,chalcedony is cloudy or translucent1 white1 yellowish-gray1 blackish-brown1 light to dark-blue1 milky-white1 and black4 ,this quartz is sometimes nearly transparent1 waxy in lustre1 and in some varieties has a light gray and transparent base with dark cloudy spots4 ,this last variety is called 8cloudy chalcedony04 ,another kind1 with gray and white stripes alternating1 is known as chalcedonyx4 ,iceland1 the ,faroe ,islands1 ,httenberg1 ,loben1 ,saxony1 ,hungary1 ,nubia1 ,nova ,scotia1 ,oberstein1 ,ceylon1 ,india1 ,siberia1 ,carinthia1 the ,hebrides1 the ,united ,states1 and ,canada are places where chalcedony is found4 ,,agates4 ,agate is an improved variety of chalcedony and comprises the following kinds4 ,banded or ribbon agate1 running in delicate parallel layers4 ,eye agate1 forming concentric rings with a dark centre1 giving the appearance of a human eye4 ,fortification agate1 running in circular parallel zigzag lines like the walls of a fortress4 ,rainbow agate is a thin or concentric structure which when cut across and held towards the light shows an iridescence4 ,moss agate1 light-gray to white and translucent to opaque agates1 display black tracings like fine moss or trees4 ,mocha or tree agates are covered with black1 brown1 or red figures1 as of trees and plants4 ,beckite or silicified coral shells1 silicified wood1 wood agate1 wood opal1 cloudy agate1 and agate jasper are some of the many varieties of this class4 ,the common carnelians1 blood-stones1 and onyxes are usually counted among the agates4 ,uruguay1 ,brazil1 ,oberstein1 ,silesia1 ,surinam1 ,india1 ,arabia1 ,saxony1 ,scotland1 the ,united ,states1 and ,canada are the principal places where agates are found4 ,,onyx ,,or ,,agate ,,onyx4 ,onyx is a variety of chalcedony in bands or strata of white1 gray1 and black1 translucent to opaque1 and generally found where agates abound4 ,the layers or bands are in even planes1 and the colors1 white and black1 white and brown1 or brown1 white1 and black1 alternate4 ,this stone is largely used for cameos1 the base being usually of black or brown1 and the engraved or upper part white- or cream-colored4 ,when one or more layers are of carnelian or sard1 the stone is called sard-onyx4 ,sard is a rich brown color inclining to red1 and when held against the light shows a red hue4 ,onyx and sard-onyx are often artificially improved by boiling the stones in honey1 oil1 or sugar water1 and then in sulphuric acid4 ,the acid carbonizes the sugar or oil which the stone has absorbed and gives it a deeper color4 ,for red1 protosulphate of iron is added1 and for a blue color to imitate lapis lazuli1 yellow prussiate of potash is added to the protosulphate of iron4 ,only the porous parts of the stones1 usually the dark parts1 absorb the sugar or oil1 and so aid the contrast of the colored with the white layers4 ,,carnelian4 ,carnelian is a clear red translucent chalcedony1 and is usually of a gray or grayish-red color4 ,several weeks of exposure to the sun's rays and subsequent heating in earthen pots enhances and deepens the color4 ,the brownish-red or dark-brown carnelian is called sardoine or sard2 the blood-red to pink varieties1 with an upper layer of white onyx1 are called carnelian onyx1 and the stones with a brown or sard base and a white top are called sard-onyx4 ,carnelians are sometimes of a yellowish-brown or yellow color1 but red to brown are the principal colors4 ,the secret of coloring agates was discovered in the early part of this century1 and about the same time agates became scarce in ,oberstein1 while large finds were made in ,brazil and ,uruguay1 especially of agates with red layers4 ,this variety comes chiefly from ,brazil4 ,besides ,uruguay and ,brazil1 carnelian is found in ,arabia and ,india4 ,the most beautiful specimens of intaglios are engraved on sardoine1 and some of the finest cameos extant are of sard and carnelian onyx4 ,,jasper4 ,jasper is an impure opaque quartz1 usually containing more iron than agate1 and lacking the quality of translucency4 ,jasper occurs in red1 brown1 ochre-yellow1 dark green1 brownish-green1 grayish-black1 and grayish-blue2 sometimes containing bands or spots or quartz formations1 and often found with regular zones or bands of various colors4 ,egyptian jasper or ,egyptian pebbles are names given to varieties that are usually brown with inner bands of lighter hue1 approaching cream in color1 and sometimes having dark bands with spots or markings4 ,egyptian jasper is found near ,grand ,cairo1 and other varieties are found in the ,urals1 ,saxony1 ,devonshire1 ,nova ,scotia1 ,canada1 and the ,united ,states4 ,the specific gravity of jasper varies from #b4ca to #b4fg2 it scratches glass1 but yields to rock-crystal4 ,,false ,,lapis4 ,false lapis is jasper or agate artificially colored blue to imitate the true lapis4 ,lapis lazuli is softer than false lapis1 being only #e to #e4e in hardness4 ,sappharine or siderite is a sapphire or sky-blue chalcedony occurring in ,salzburg4 ,nicolo is a variety of onyx with a black or brown base and a band or layer of bluish-white on top4 ,the upper layer is not flat1 but convex1 and is always thicker than the lower one4 ,,hematite4 ,hematite was once largely used to engrave upon1 many of the ancient intaglios being on this mineral4 ,it is now cut to simulate black pearls1 and is also used in the cheaper jewelry1 both engraved and cut cabochon4 ,hematite has the hardness of #e4e to #f4e1 and specific gravity1 #d4b to #e4c2 it is opaque1 and shows a red streak when scratched4 ,it is composed of3 ,iron #gj ,oxygen #cj ,the colors of hematite are dark-steel gray to iron-black1 and sometimes brownish- to blood-red4 ,the lustre is highly metallic1 with slight iridescence4 ,the island of ,elba1 ,france1 ,switzerland1 ,italy1 ,norway1 ,sweden1 ,bohemia1 ,england1 ,brazil1 ,chili1 ,canada1 ,spain1 and the ,united ,states are places where hematite is found4 ,the ,germans call this mineral 8blood-stone10 and it is also known as specular iron ore and iron glance4 ,,obsidian4 ,obsidian1 or volcanic glass1 does not occupy a high position as a gem or as an ornamental stone1 but its antiquity and occasional use among the agates and semi-precious stones will justify its mention4 ,this mineral is a melted lava1 and consists of silex1 alumina1 and a little potassa1 soda1 and oxide of iron4 ,obsidian is #f to #g in hardness1 has a specific gravity of #b4be to #b4h1 is sometimes transparent but mostly translucent to opaque1 and is vitreous to metallic in lustre4 ,it is brittle and not easily attacked by acids4 ,it melts before the blow-pipe and takes a high polish4 ,obsidian comes from volcanoes1 and is found in ,iceland1 ,teneriffe1 ,lepare islands1 ,peru1 ,mexico1 ,sicily1 and on all volcanoes4 ,the color is velvety-black to gray1 brown1 greenish-black1 yellow1 blue1 bottle-green1 and white1 seldom red1 and often with black or yellow spots or veinings4 ,iceland agate lava1 volcanic lava1 and royal agate are all obsidian4 ,,malachite4 ,malachite although sometimes used for jewelry1 is now more largely employed for mosaic work and ornamental vases1 and is sufficiently costly and rare to be classed amongst the precious stones4 ,malachite is #c4e to #d in hardness2 has a specific gravity of #c4f to #d2 is translucent to opaque2 the lustre is vitreous to adamantine4 ,it is attacked by acids1 and melts before the blow-pipe4 ,it is composed of3 ,carbonic acid #bj4 ,protoxide of copper #ga4h ,water #h4 ,malachite occurs in emerald or verdigris green color1 sometimes in alternating stripes of different shades of green1 and occasionally in leek- to blackish-green4 ,malachite is found in ,russia1 ,france1 the ,tyrol1 ,england1 ,scotland1 ,ireland1 ,germany1 ,africa1 ,chili1 ,australia1 and the ,united ,states4 ,the finest specimens are found in the ,urals--a block three and a half feet square1 being valued at #ebe1jjj roubles4 ,,jet4 ,the making of jet or mourning jewelry was once a very large industry in ,france and ,england1 and even now ,whitby jet is well known in commerce4 ,jet is a species of bituminous coal 7cannel coal7 which can be cut with a knife4 ,the hardness is #a to #b4e2 specific gravity1 #a4ce2 its lustre is not very high1 and color pitch-black4 ,it is found in ,england1 ,france1 ,hesse1 ,spain1 ,italy1 and ,prussia4 ,,amber4 ,amber is a fossil1 and is not to be classed amongst minerals1 but this material has always been used as an ornament1 and a few notes will not be out of place here4 ,this vegetable fossil1 which has been known to the world for ages1 the ,greeks called electron4 ,it is very light1 having a specific gravity of #a4jfe to #a4jh1 and is #b to #b4e in hardness4 ,the principal color is yellow1 in various shades1 sometimes running into white or reddish-brown and black4 ,amber is transparent to translucent1 possesses single refraction1 a resinous lustre to a high degree1 becomes electric by rubbing1 and burns readily before the blow-pipe4 ,amber when heated becomes soft and pliable4 ,amber is composed of3 ,carbon #gi4 ,hydrogen #aj4e ,oxygen #aj4e ,amber is imitated by gum copal1 and even the insect enclosures which occur in real amber are copied4 ,these imitations can be detected by placing the specimen in water or alcohol4 ,this is also a good test for pieces of real amber that have been melted or glued together4 ,amber is thrown up by the sea1 in rivers near the sea1 or on the sea-shore1 and has been found in nearly all parts of the world4 ,the ,russian1 ,baltic1 and ,sicilian coasts have yielded the larger portion of the production1 but supplies come also from ,galizia1 the ,urals1 ,poland1 ,china1 and the ,united ,states4 ,for ornamental purposes the faceted amber beads are largely used1 but of late years these have been closely imitated in glass4 ,,coral4 ,coral1 although not a precious stone1 has been largely used in jewelry1 and as some of this beautiful substance is very valuable1 a few words will not come amiss4 ,red or precious coral is the work of a family of zophytes which live mostly in cavities of rock in the sea4 ,these polyps build their homes at a depth of two to seven hundred feet under the surface of the sea1 and although the single groups of coral are sometimes several feet long1 the usual size is about twelve inches high1 and about one inch at the thickest part of any single branch4 ,coral is usually red1 and rarely white or black1 while the pale rose-pink is the most esteemed color4 ,coral is mostly found at ,calle1 off the coast of ,africa1 but also on the coasts of ,tunis1 ,algiers1 ,corsica1 ,barbary1 ,majorca1 and ,minorca4 ,coral fishing-vessels leave ,italy the beginning of ,march and return from the ,african coast in ,october2 at one time as many as four hundred vessels were engaged in this industry4 ,,table ,,of ,,hardness ,,and ,,specific ,,gravity4 ,,hardness4 ,,specific ,,gravity4 ,achroite #g4 -- #g4e #c4 -- #c4a ,alexandrite #h4e #c4fe -- #c4h ,almandine #g4e #d4 -- #d4b ,almandite #g4e #d4 -- #d4b ,amber #b4 -- #b4e #a4jfe -- #a4jh ,apatite #d4e -- #e4 #b4ie -- #c4be ,axinite #f4e -- #g4 #c4 -- #c4c ,beryl #g4e -- #h4 #b4fg -- #b4gc ,bobrowska garnet #f4 #c4he ,bohemian #g4e #c4fi -- #c4gh ,brazilian emerald #g4 -- #g4e #c4 -- #c4a sapphire #g4 -- #g4e #c4 -- #c4a ,cachelong #e4e -- #f4 #b4 -- #b4a ,cat's-eye #h4e #c4 -- #c4h ,ceylon chrysolite #g4 -- #g4e #c4 -- #c4a peridot #g4 -- #g4e #c4 -- #c4a ,chrysoberyl #h4e #c4fe -- #c4h ,chrysolite #f4e -- #g4 #c4c -- #c4e ,chrysoprase #g4 #b4ef ,cinnamon stone #f4e #c4e -- #c4ef ,cyanite #e4 -- #g4 #c4de -- #c4g ,cymophane #h4e #c4fe -- #c4h ,demantoide #f4 #c4he ,diamond #aj4 #c4e -- #c4f ,dichroite #g4 -- #g4e #b4ef -- #b4fg ,diopside #e4 -- #f4 #b4i -- #c4e ,emerald #g4e -- #h4 #b4fg -- #b4gc ,epidote #f4 -- #g4 #c4cb -- #c4ej ,essonite #f4e #c4e -- #c4ef ,euclase #g4e #c4a ,fluor spar #d4 #c4a -- #c4b ,garnet #e4 -- #h4 #c4ae -- #d4c ,grossularite #f4e #c4e -- #c4ef ,hematite #e4f -- #f4e #d4b -- #e4c ,hiddenite #f4e -- #g4 #c4ac -- #c4ai ,hyacinth #g4e #d4d -- #d4g ,hydrophane #e4e -- #f4 #b4 -- #b4a ,hypersthene #f4 #c4c -- #c4d ,idocrase #f4e #c4ce -- #c4de ,indicolite #g4 -- #g4e #c4 -- #c4a ,jacinth #g4e #d4d -- #d4g ,jargoon #g4e #d4d -- #d4g ,jasper #g4 #b4ca -- #b4fg ,jet #b4e #a4ce ,labrador #f4 #b4fb -- #b4gf hornblende #f4 #c4c -- #c4d ,lapis lazuli #e4 -- #e4e #b4ch -- #b4db ,malachite #c4e -- #d4 #c4f -- #d4 ,moonstone #f4 -- #f4e #b4d -- #b4f ,obsidian #f4 -- #g4 #b4be -- #b4h ,olivine #f4e -- #g4 #c4c -- #c4e ,opal #e4e -- #f4 #b4 -- #b4a ,oriental amethyst #i4 #c4i -- #d4a aquamarine #i4 #c4i -- #d4a chrysolite #i4 #c4i -- #d4a emerald #i4 #c4i -- #d4a hyacinth #i4 #c4i -- #d4a topaz #i4 #c4i -- #d4a ,pearl #b4e -- #b4g ,peridot #f4e -- #g4 #c4c -- #c4e ,phenacite #g4e -- #h4 #b4if -- #c4 ,pyrope #g4e #c4fi -- #c4gh ,quartz #g4 #b4e -- #b4h cat's-eye #f4 -- #f4e #b4fe ,rose quartz #g4 #b4fe -- #b4ge ,rubellite #g4 -- #g4e #c4 -- #c4a ,ruby #i4 #c4i -- #d4a cat's-eye #i4 #c4i -- #d4a ,sapphire #i4 #c4i -- #d4a cat's-eye #i4 #c4i -- #d4a ,siberite #g4 -- #g4e #c4 -- #c4a ,sphene #e4 -- #e4e #c4d -- #c4ef ,spinel #h4 #c4e -- #c4f ,spodumene #f4e -- #g4 #c4ac -- #c4ai ,star ruby #i4 #c4i -- #d4a sapphire #i4 #c4i -- #d4a topaz #i4 #c4i -- #d4a ,sunstone #f4 -- #g4 #b4ef -- #b4gb ,syrian garnet #g4e #d4 -- #d4db ,titanite #e4 -- #e4e #c4d -- #c4ef ,topaz #h4 #c4d -- #c4f ,tourmaline #g4 -- #g4e #c4 -- #c4a ,turquois #f4 #b4f -- #b4h ,uwarowite #g4e #c4da -- #c4eb ,vesuvianite #f4e #c4ce -- #c4de ,water sapphire #g4 -- #g4e #b4ef -- #b4fg ,,general ,,index4 ,achroite1 #fd ,actinolite1 #bi ,adularia1 see moonstone ,agate jasper1 #abj ,agate onyx1 see onyx ,agate1 see quartz1 #ajf1 #aai1 #abb1 #abc1 #abd1 #abf ,alexandrite1 #h1 #ed1 #ef ,almandine1 #i1 #cj1 #hj ,almandite1 #bi1 #hj ,amazon stone1 #ag1 #hh1 #ia ,amber1 #ag1 #abh ,american ruby1 #hj1 #hc ,amethyst1 #h1 #i1 #af1 #ag1 #dd1 #di1 #ajg1 #aaj1 #aaa ,amethystine quartz1 see amethyst ,antimony1 #bi ,apatite1 #ai1 #hg ,aquamarine1 #h1 #af1 #ec ,aquamarine chrysolite1 #ec ,arizona ruby1 #hj1 #hc ,asterias1 see star sapphires ,aurora red sapphire1 see ,oriental hyacinth ,avanturine1 #aac1 #aad ,avanturine felspar1 see sunstone ,axinite1 #ag1 #ajb ,balas ruby1 #dh ,banded agate1 #aai ,beckite1 #abj ,beryl1 #ad1 #af1 #ag1 #dd1 #ej1 #eb1 #ec1 #hg ,blood-stone1 see heliotrope see hematite ,bobrowska garnet1 #hj1 #hc ,bohemian garnet1 #hj #hb diamond1 see rock-crystal topaz1 see yellow quartz ,bone turquois1 #fb ,bort1 #ch ,brazilian aquamarine1 #he emerald1 #fd1 #fg ruby1 #he sapphire1 #he topaz1 see topaz ,bronzite1 #cj ,cachelong1 #fi1 #gj ,cairngorm1 #ajg1 #aaa ,calcite1 #ai ,cameo1 #h ,cannel coal1 see jet ,cape garnet1 #hj1 #hc ,cape ruby1 #hj1 #hc ,carbon1 #cg ,carbonate1 see carbon ,carbuncle1 #hj #hc ,carnelian1 #ag1 #aac1 #abc1 #abd onyx1 #abb ,cat's-eye1 corundum1 #h1 #ed1 #eg1 #aae1 #aaf quartz1 #ah1 #eh1 #ajg1 #aac1 #aad1 #aae ,ceylon cat's-eye1 see corundum cat's-eye chrysolite1 #fd1 #gi opal1 see moonstone peridot1 #fd ,ceylonite1 #dg ,chalcedonyx1 see chalcedony ,chalcedony1 #h1 #i1 #af1 #ag1 #aac1 #aah1 #aai1 #abj1 #abb1 #abd ,chrysoberyl1 #af1 #ag1 #de1 #ed1 #ef1 #eg1 #gi ,chrysolite1 #ag1 #cj1 #ec1 #eh1 #gh1 #hg1 #ii1 #ajg ,chrysoprase1 #ag1 #ajg1 #aac1 #aag ,cinnamon stone1 see grossularite ,cleavage1 #aj ,cloudy agate1 #abj chalcedony1 see chalcedony ,colors1 #af ,coral1 #acj ,cordierite1 see dichroite ,corundum1 #i1 #ag1 #ci1 #de1 #dg1 #dh1 #di ,crocidolite1 #e1 #ah1 #aac1 #aae ,crystallization1 #aj ,cutting1 #cb ,cyanite1 #ag1 #ib ,cymophane1 #ed1 #ef1 #eg ,decimal system1 #bh ,demantoide1 see ,bobrowska garnet ,diamond1 #i1 #aa1 #ab1 #ad1 #ae1 #ag1 #ah1 #bj1 #ca1 #cb1 #cc1 #ce1 #dj1 #da1 #di1 #ea1 #eb1 #fj1 #ge1 #aja1 #aji ,dichroiscope1 #ad ,dichroite1 #ig ,diopside1 #ajc ,egyptian jasper1 #abc pebbles1 see ,egyptian jasper ,electricity1 #ca ,emerald1 #h1 #i1 #af1 #ag1 #ah1 #ca1 #dd1 #ea1 #hg1 #ie1 #ajg ,epidote1 #ag1 #aja ,essonite1 see grossularite ,euclase1 #ii ,eye agate1 #aai ,false emerald1 see fluor spar lapis1 #abd ruby1 see fluor spar topaz1 see fluor spar and yellow quartz ,fancy sapphires1 #dd ,felspar1 #bj1 #hh1 #ia ,fish-eye1 see moonstone ,flint1 #aac ,fluor spar1 #ag1 #ai1 #ca1 #ajd ,fortification agate1 #aai ,fossil turquois1 #fc ,fracture1 #aa ,fusibility1 #bh ,garnet1 #ab1 #ad1 #ae1 #ag1 #ba1 #cb1 #db1 #ec1 #fd1 #hj1 #ajg ,girasol1 #df ,glass1 #ae ,golden beryl1 #ed ,goldstone1 see avanturine ,goutte d'eau1 #he ,green felspar1 see ,amazon stone garnet1 #hj1 #ii sapphire1 see ,oriental emerald ,greenish-yellow sapphire1 see ,oriental chrysolite ,grossularite1 #cj1 #hj1 #hb ,hair-stone1 see cairngorm ,heliotrope1 #aac1 #aaf1 #aah1 #abj ,hematite1 #ah1 #abd ,hiddenite1 #ie ,hornstone1 #aac ,hungarian cat's-eye1 see quartz cat's-eye ,hyacinth1 #db1 #eh1 #ei ,hydrophane1 #fi1 #gj ,hypersthene1 #aje ,iceland lava1 see obsidian spar1 #ad ,idocrase1 #ag1 #ih ,indian topaz1 see yellow quartz ,indicolite1 #fd1 #fg ,intaglio1 #h ,iolite1 see dichroite ,iridescent quartz1 see rose quartz ,jacinth1 #eh1 #ei1 #hb ,jargoon1 #eh1 #ei ,jasper1 #ag1 #ajf1 #aac1 #abc1 #abd ,jet1 #af1 #abh ,labrador1 #af1 #hh1 #ia hornblende1 see hypersthene ,labradorite1 see ,labrador ,labrador spar1 see ,labrador ,lake ,george diamond1 see rock-crystal ,lapis lazuli1 #ag1 #ic1 #abd ,lava1 see obsidian ,light-green sapphire1 see ,oriental aquamarine ,love arrows1 see cairngorm ,lustre1 #ag ,magnetism1 #cj ,malachite1 #ag1 #abg ,mica1 #aa ,mineral turquois1 #fa1 #fb ,mocha agate1 #abj ,moonstone1 #ag1 #ch1 #hi1 #ia1 #aji1 #aab ,moss agate1 #abj ,mother of emerald1 see prase ,natrolite1 #bi ,needle-stone1 see cairngorm ,nicolo1 #abd ,obsidian1 #aj1 #af1 #abe ,occidental cat's-eye1 see quartz cat's-eye diamond1 see rock-crystal topaz1 see yellow quartz turquois1 #fb ,odontolite1 #ag1 #fb il de buf1 see ,labrador ,oligoclase1 see sunstone ,olivine1 #ag1 #ah1 #ec1 #gh1 #hd ,onyx1 #h1 #ajf1 #ajg1 #aac1 #abj1 #abd ,opal1 #h1 #i1 #aj1 #af1 #ag1 #ah1 #cj1 #fi1 #ajj1 #ajb1 #ajg common1 see opal fire1 noble1 ,opaline felspar1 see ,labrador ,oriental amethyst1 #ci1 #dd aquamarine1 #ci1 #dd chrysolite1 #ci1 #dd2 see also chrysoberyl emerald1 #ci1 #dd1 #ea hyacinth1 #ci1 #dd opal1 see opal topaz1 #ci1 #dd1 #hg turquois1 #fa ,orthoclase1 #bi1 #hg ,orthose1 see moonstone ,ox-eye1 see ,labrador ,pearl1 #ga baroque1 #gd black1 #gc1 #abd bouton1 #gd pink1 #gg ,pebble diamond1 see rock-crystal ,peridot1 #af1 #gh ,persian turquois1 #fb ,phenacite1 #aja ,phosphorescence1 #ca ,plasma1 #aac1 #aah ,pleiochroism1 #ad ,pleonast1 #dg ,polarization of light1 #ac ,polishing1 #cb ,prase1 #ag1 #aac1 #aag1 #aah ,precious schorl1 see tourmaline ,purple sapphire1 see ,oriental amethyst ,pyrope1 #cj1 #hj1 #hb ,quartz1 #i1 #af1 #bj1 #bb1 #db1 #ej1 #ajf1 #abc cat's-eye1 see cat's-eye quartz ,rainbow agate1 #aai quartz1 #aab ,reconstructed rubies1 #dc turquois1 #fd ,red quartz1 see quartz sapphire1 see ruby ,refraction1 #ab ,rhinestone1 see rock-crystal ,ribbon agate1 #aai ,rock-crystal1 #ag1 #ch1 #ia1 #aji1 #aab salt1 #aa1 #ai ,rose quartz1 #ag1 #aac ,rose topaz1 see topaz ,royal agate1 see obsidian ,rubellite1 #fd1 #fe ,rubicelle1 #dh ,ruby1 #ad1 #ae1 #af1 #ag1 #ah1 #ba1 #bf1 #cb1 #cg1 #ci1 #dj1 #ec1 #fd1 #ajg ,ruby1 cat's-eye1 #ci1 #df spinel1 see spinel ,saganite1 see cairngorm ,saphir d'eau1 see dichroite ,sappare1 see cyanite ,sapphire1 #af1 #ag1 #bj1 #ba1 #cg1 #ch1 #ci1 #da1 #db1 #dc1 #ea1 #eb1 #ic1 #ih ,sapphire1 cat's-eye1 #ci1 #df ,sapphirine1 #dh1 see false lapis ,sard1 #aba1 #abb ,sardoine1 see sard ,sardonyx1 #aba1 #abb ,saxony topaz1 #he ,siberian aquamarine1 #ec topaz1 #he ,siberite1 #fd ,siderite1 see false lapis ,silicified coral shells1 see beckite wood1 #abj ,slave's diamond1 see topaz ,smoky-quartz1 see cairngorm topaz1 #af1 #ag ,spanish topaz1 see yellow quartz ,specific gravity1 #ba ,sphene1 #ajj ,spinel1 #ab1 #ad1 #ae1 #ag1 #ah1 #ba1 #db1 #df ,spodumene1 #ie1 #if ,star ruby1 #ci1 #de ,star sapphire1 #ci1 #de topaz1 #ci1 #de ,streak1 #ah ,sunstone1 #df1 #hh1 #hi1 #ij ,syrian garnet1 #hj ,talc1 #ai ,titanite1 see sphene ,tiger-eye1 see crocidolite ,topaz1 #h1 #i1 #af1 #ag1 #bj1 #ca1 #cb1 #ch1 #db1 #di1 #ej1 #eh1 #hd1 #ajg1 #aaa ,tourmaline1 #ac1 #af1 #ag1 #ba1 #cb1 #db1 #ec1 #fd1 #ajg ,transparency1 #cj ,tree agate1 see ,mocha agate ,turquois1 #i1 #aj1 #ag1 #ah1 #cj1 #fj1 #ajg ,uwarowite1 #hj1 #hc ,venus hair-stone1 see cairngorm ,vermeille1 #hj1 #hc ,vesuvianite1 see idocrase ,volcanic glass1 see obsidian lava1 ,water opal1 see moonstone sapphire1 see dichroite ,weight1 #bg ,white spinel1 see spinel ,wood agate1 #abj opal1 #abj ,yellow quartz1 #aaa sapphire1 see ,oriental topaz ,zircon1 #i1 #af1 #ag1 #ah1 #ch1 #di1 #eh