,educational ,s]ies #e ,guide to ,,rocks ,,& ,,m9]als ,,( ,,ill9ois ,ill9ois ,/ate ,geological ,survey ,illu/ration3 uncaption$ ,,/ate ( ,,ill9ois ,william ,g4 ,/ratton1 ,gov]nor ,,dep>tm5t ( ,,regi/ration & ,,education ,v]a ,m4 ,b9ks1 ,director ,fir/ pr9t+ #aiei ,second pr9t+ #aifj ,,ill9ois ,,/ate ,,geological ,,survey ,john ,c4 ,frye1 ,*ief ,,urbana1 ,,ill9ois ,pr9t$ by ,au?ority ( ! ,/ate ( ,ill9ois ,guide to ,,rocks ,,& ,,m9]als ,,( ,,ill9ois ,ill9ois has s long be5 kn[n z ! ,prairie ,/ate t at fir/ glance x seems a mo/ unlikely place 9 :i* to collect rock & m9]al specim5s4 ,b ,ill9ois has a surpris+ weal? ( rock & m9]al res\rces1 n only to be collect$ z int]e/+ specim5s b to be put to practical & pr(itable use4 ,! ri* prairies t gave ! /ate its nickname are !mselves d]iv$ f anci5t rocks1 worn & *ang$ by millions ( ye>s ( action by wea!r1 wat]1 w9d1 plants1 & animals4 ,unmeasur$ dep?s ( rock und]lie ! prairies1 hills1 & valleys1 & 9 "s p>ts ( ! /ate are expos$ 9 outcrops1 canyons1 & riv] valleys4 ,b\ld]s & gravel br\ght 9 by ! glaci]s ?\s&s ( ye>s ago are /rewn ov] _m p>ts ( ! /ate4 ,^! res\rces are ( great value4 ,besides ! ri* agriculture bas$ on ! rock-d]iv$ soil1 mu* ( our indu/ry1 manufactur+1 & transportation is dep5d5t on rock & m9]al mat]ials4 ,e c\nty 9 ,ill9ois possesses "s rocks & m9]als t ei!r are be+ us$ or h pot5tial future value4 ,! ,ill9ois ,/ate ,geological ,survey sev]al ye>s ago began to prep>e sets ( typical rocks & m9]als ( ,ill9ois = use by ! s*ools & o!r educational gr\ps 9 ,ill9ois4 ,?is booklet is design$ to furni% a brief geological backgr\nd & explanation ( ^! common ,ill9ois rocks & m9]als4 ,x also %\ld be useful to ! /ud5t or amateur int]e/$ 9 mak+ 8 own collection4 ,ev5 ?\gh ,ill9ois has no m\nta9 ranges or deep canyons1 ! geology ( ! /ate has _m complexities4 ,9 fact1 ! v flatness ( our topography is a complicat+ factor because 9 ord] to /udy ! geology at _m places 9 ! /ate x is necess>y to use in=mation f m9es & descriptions 7logs7 & samples 7cores7 ( ! rock p5etrat$ dur+ drill+ ( deep wells4 ,!re are also geophysical me?ods ( le>n+ some?+ ab\t ! rocks b5ea? ! surface4 ,illu/ration3 ,fig4 #a4--;,geologic map ( ,ill9ois4 ,,cambrian ,,ordovician ,,ordovician-,,silurian ,,ordovician-,,silurian ,,"u ,,drift ,,devonian-,,mississippian ,,p5nsylvanian ,,"u ,,drift ,,cretace\s-,,t]ti>y ,,key ,wiscons9 glacial drift ,ill9oian glacial drift ,p5nsylvanian b\nd>y ,! complexity ( ,ill9ois geology is n produc$ by ! upturn+ & %>p fold+ ( rock lay]s su* z c be se5 9 ! ,rocky ,m\nta9s1 b r by ! *anges 9 composition1 ?ickness1 & "* ( ! rock lay]s t are only g5tly w>p$ or relatively flat4 ,at sev]al places 9 ! /ate1 especially 9 ! s\!rn "p1 faults1 or breaks1 9 ! rock lay]s d occur1 b ov] mu* ( our area ?is is n common4 ,! pres5ce ( usable m9]als at consid]able dep? is kn[n at _m places2 coal is m9$ f dep?s great] ?an #hjj feet1 & oil is produc$ f saturat$ rock lay]s1 call$ pay zones1 sev]al ?\s& feet bel[ ! surface4 ,lead & z9c ores1 fluorsp>1 silica s&1 lime/one1 s&1 gravel1 clay1 & %ale are all produc$ at %all[] dep?s4 ,h[ev]1 ! /ud5t c see only ^? rocks & m9]als t are to be f\nd at or ne> ! surface4 ,= t reason ! foll[+ p>agraphs describ+ _! geologic occurr5ce deal only ) surface geology4 ,! y\nge/ ( ! major geologic divisions ( our rocks is call$ ! ,plei/oc5e1 :i* is ! sci5tific "n = ! 8,ice ,age0 deposits4 ,dur+ ?is relatively rec5t p]iod ( geologic "t1 :i* began ab\t a million ye>s ago1 glaci]s fl[$ s\?w>d f ,canada & spread a lay] ( 8glacial drift0 ov] all ( ! /ate except ! nor?we/ corn]1 ! s\?we/ edge ( ! /ate along ! ,mississippi ,riv]1 & extreme s\!rn ,ill9ois 7fig4 #a74 ,mo/ ( ! glacial deposits t we see 7 =m$ by ! la/ two ( ! f\r major p]iods ( glacial advance1 ! ,ill9oian & ! ,wiscons94 ,! ,ill9oian 0 ! mo/ ext5sive1 rea*+ z f> s\? z ,c>bondale & ,h>risburg4 ,! ,wiscons91 s call$ because its deposits are s widely spread 9 t /ate1 rea*$ only to ,mattoon & ,peoria4 ,! glacial drift is ! y\nge/ & upp]mo/ ( ! divisions ( ! rock column 7fig4 #b74 ,)9 ! drift c be f\nd ! wide/ div]sity ( rock & m9]al types--qu>tzite1 s*i/1 & o!r metamorphic rocks2 granite1 gabbro1 & o!r igne\s rocks2 & ( c\rse ! s$im5t>y rocks1 lime/one1 dolomite1 s&/one1 %ale1 & ev5 pieces ( coal1 :i* occur 9 b$d$ lay]s ( ! old] rocks 9 ,ill9ois4 ,s& & gravel 7 c>ri$ & deposit$ by fl[+ /reams be=e1 dur+1 & aft] glaciation1 b ! major deposits 7 made :ile ! glaci]s 7 melt+4 ,!y conta9 a wide v>iety ( rock & m9]al types4 ,illu/ration3 ,figure #b--;,diagram ( lay]s ( rocks 9 ,ill9ois4 ,era ,g5]al ,types ( ,rocks ,p]iod or ,sy/em & ,?ickness ,epo* ,,c5ozoic 8,rec5t ,life0 ,age ( ,mammals ,quat]n>y #j-ejj ,plei/oc5e or ,glacial ,age ,rec5t--alluvium 9 riv] valleys ,glacial till1 glacial outwa%1 gravel1 s&1 silt lake deposits ( clay & silt1 loess & s& dunes2 cov]s ne>ly all ( /ate except nor?we/ corn] & s\!rn tip ,t]ti>y #j-ejj ,plioc5e ,*]t gravel2 pres5t 9 nor!rn1 s\!rn1 & we/]n ,ill9ois ,eoc5e ,mo/ly micace\s s& ) "s silt & clay2 pres5t only 9 s\!rn ,ill9ois ,paleoc5e ,mo/ly clay1 little s&2 pres5t only 9 s\!rn ,ill9ois ,,mesozoic 8,middle ,life0 ,age ( ,reptiles ,cretace\s ,mo/ly s&1 "s ?9 b$s ( clay &1 #j-cjj locally1 gravel2 pres5t only 9 s\!rn ,ill9ois ,,paleozoic 8,anci5t ,life0 ,age ( ,amphibians & ,e>ly ,plants ,p5nsylvanian ,l>gely %ale & s&/one ) b$s ( coal1 #j-c1jjj lime/one1 & clay 78,coal ,measures07 ,mississippian ,black & gray %ale at base2 middle zone ( #j-c1ejj ?ick lime/one t grades to silt/one1 *]t1 & %ale2 upp] zone ( int]b$d$ s&/one1 %ale & lime/one ,age ( ,fi%es ,devonian ,?ick lime/one1 m9or s&/ones & %ales2 #j-a1ejj l>gely *]t & *]ty lime/one 9 s\!rn ,ill9ois ,age ( ,inv]tebrates ,silurian ,pr9cipally dolomite & lime/one #j-a1jjj ,ordovician ,l>gely dolomite & lime/one b conta9s #ejj-b1jjj s&/one1 %ale1 & silt/one =mations ,cambrian ,*iefly s&/ones ) "s dolomite & %ale2 #a1ejj-c1jjj expos$ only 9 small areas 9 nor?-c5tral ,ill9ois ,,ar*eozoic & ,,prot]ozoic ,igne\s & metamorphic rocks2 kn[n 9 ,ill9ois only f deep wells ,z %[n by ! diagrammatic rock column 7fig4 #b71 rocks plac$ 9 ! divisions call$ e>ly ,c5ozoic & ,mesozoic are next 9 age to ! ,plei/oc5e4 ,! map 7fig4 #a7 %[s t ! ,c5ozoic & ,mesozoic rocks occur only 9 ! extreme s\!rn tip ( ,ill9ois because only t "p ( ,ill9ois 0 cov]$ by a nor?w>d ext5sion ( ! =]unn] ( ! ,gulf ( ,mexico 9 :i* ! deposits ( s&1 gravel1 & clay 7 laid d[n4 ,! next old] division ( ,ill9ois rocks is call$ ,p5nsylvanian--or 8,coal ,measures0--because dur+ ! la/ c5tury !y 7 fir/ ext5sively describ$ by geologi/s work+ 9 ,p5nsylvania4 ,! ,p5nsylvanian is "o ( our mo/ important gr\ps ( rock /rata because x conta9s all ( our m9able coal b$s1 z well z important deposits ( lime/one1 %ale1 clay1 s&/one1 & "s oil & gas4 ,! ,p5nsylvanian rocks are v widespread 9 ,ill9ois1 occurr+ "u ! glacial drift f dep?s ( a few feet to sev]al hundr$ feet ?r\gh\t ab\t two-?irds ( ! glaciat$ area 7fig4 #a74 ,next bel[ ! ,p5nsylvanian are ! ,mississippian rocks4 ,we 9 ,ill9ois are p>ticul>ly int]e/$ 9 ?is division ( rocks because !y take _! "n f ! excell5t exposures along ! ,mississippi ,riv] valley 9 we/]n ,ill9ois1 s\!a/]n ,i[a1 & ea/]n ,miss\ri4 ,!y are compos$ ( ext5sive b$s ( lime/one & *]ty lime/one1 s&/one1 & %ale4 ,mississippian rocks are ( great economic importance 9 ! /ructural area kn[n z ! ,ill9ois ,bas91 :]e !y are ! mo/ important oil produc+ rocks4 ,!y also conta9 our fluorsp> deposits & along ! valley bluffs are an excell5t s\rce ( lime/one = qu>ry+4 ,rocks old] ?an ! ,mississippian--except = small areas along ! ,mississippi & ,ill9ois ,riv] valleys--are f\nd at ! surface only 9 ! nor!rn qu>t] ( ! /ate & locally 9 ,h>d9 ,c\nty ne> ! s\!rn tip ( ! /ate4 ,!y are none!less economically important because f ^! old] rocks are produc$ lead & z9c1 "s oil & gas1 silica s&1 lime/one1 dolomite1 & %ale4 ,on ! g5]aliz$ rock column 7fig4 #b7 ^! old] rocks are gr\p$ into two units4 ,! upp]mo/ conta9s ! ,devonian & ,silurian & ! l[] conta9s ! ,ordovician & ,cambrian4 ,9 g5]al !y include dolomite1 lime/one1 & %ale1 ) s&/one at sev]al places1 especially 9 ! l[] unit4 ,,description ,,( ,,rocks ,,& ,,m9]als ,! t]ms m9]al & rock are (t5 confus$4 ,!y are frequ5tly us$ toge!r & ! mat]ials !y describe are closely relat$4 ,9 g5]al1 a m9]al is a naturally occurr+ *emical elem5t or comp\nd =m$ by inorganic processes1 :]eas a rock is a mixture ( p>ticles or gra9s ( sev]al m9]als4 ,h[ev]1 :5 we ref] to m9]al res\rces or indu/rial m9]als1 we g5]ally include mat]ials t are te*nically rocks--su* z lime/one1 dolomite1 %ale--& also coal & oil t are 9 fact organic sub/ances4 ,on ! o!r h&1 we include 9 ! rock category high purity s&/one t is compos$ almo/ entirely ( "o m9]al 7qu>tz7 & high purity lime/one t is compos$ l>gely ( ! m9]al calcite4 ,,m9]als ,a few m9]als are compos$ ( only "o elem5t1 su* z diamond 7c>bon7 & native copp]1 b mo/ m9]als are *emical comp\nds t conta9 sev]al elem5ts4 ,mo/ m9]als gr[ into di/9ctive %apes if !y are free to gr[4 ,a famili> example is ! =mation ( salt cry/als t gr[ on a sauc] ( evaporat+ salt wat]4 ,! di/9ctive %apes ( cry/als are call$ _! habits1 & ! flat surfaces t develop are call$ cry/al faces1 ! angles ( :i* may be us$ to id5tify ! m9]al4 ,! individual atoms ( a cry/al always arrange !mselves 9 ! same way1 s t ea* m9]al breaks *>act]i/ically4 ,"s m9]als break m easily 9 p>ticul> directions & pres5t a flat1 smoo? surface4 ,?is *>act]i/ic is call$ cleavage & ! cleavage surfaces1 al?\gh sometimes confus$ ) cry/al faces1 may be useful = id5tify+ a p>ticul> m9]al4 ,! mann] 9 :i* a m9]al breaks :5 ! brok5 surface does n include cleavage surfaces is call$ its fracture1 & ?is too may give a clue to ! id5tification ( ! m9]al4 ,!re are o!r physical features useful 9 id5tify+ m9]als4 ,"s ( !m1 su* z color1 are q obvi\s4 ,! color ( ! p[d] left :5 a m9]al is scrap$ on a r\gh1 :ite surface1 su* z unglaz$ porcela9 or tile1 is call$ /reak4 ,lu/] ref]s to ! brightness ( light reflect$ f ! m9]al's surface4 ,transp>5cy & transluc5cy ref] to ! m9]al's ability to transmit light1 & t5acity is a measure ( its t\ghness4 ,two special physical *>act]i/ics ( m9]als are important to _! id5tification--specific gravity & h>dness4 ,specific gravity simply means ! ratio ( ! weight ( ! m9]al to an equival5t volume ( wat]4 ,= example1 if a m9]al has a specific gravity ( #d1 !n a cubic in* ( ! m9]al weighs z mu* z #d cubic in*es ( wat]4 ,h>dness is measur$ by ! ability ( "o m9]al to scrat* ano!r1 & a set ( t5 /&>d m9]als has be5 select$ = det]m9+ ?is *>act]i/ic4 ,! li/+ bel[1 f s(t to h>d1 is kn[n z ,mohs scale4 #a--,talc #b--;,gypsum #c--;,calcite #d--;,fluorite #e--;,apatite #f--,or?oclase #g--,qu>tz #h--,topaz #i--;,corundum #aj--;,diamond ,a r\gh measure ( h>dness c be made by us+ h&y objects4 ,y\r f+]nail has a h>dness rang+ f #b to #c1 a p5ny is a little h>d] ?an #c1 w9d[ glass ranges f less ?an #e to approximately #f 9 h>dness1 & a knife blade is g5]ally 9 ! range ( #e to #f4 ,,rocks ,rocks1 be+ mixtures ( m9]als1 are m complex ?an m9]als & are !re=e classifi$ 9 a m complicat$ way4 ,! broade/ gr\p+ ( rocks is bas$ on ! orig9 ( ! rock r ?an on ! m9]als t compose x4 ,9 ?is s*eme all rocks are divid$ into ?ree g5]al gr\ps1 igne\s1 s$im5t>y1 & metamorphic4 ,! igne\s rocks are m5tion$ fir/ because !y are produc$ directly f hot liquids t come f deep )9 ! e>?4 ,^! hot liquids are ess5tially molt5 rock & are call$ magmas4 ,:5 !y cool1 ! elem5ts ( ! individual m9]als come toge!r & cry/allize1 z wat] cry/allizes into ice on a w9t] day4 ,diff]5t m9]als cry/allize1 or 8freeze01 at diff]5t temp]atures s t if ! magma cools sl[ly "s individual gra9s h opportunity to gr[ l>g] ?an o!rs4 ,if ! magma cools quickly1 z does lava or basalt1 ! sep>ate m9]al gra9s w be small4 ,igne\s rocks are classifi$ on ! basis ( ! size & arrangem5t ( ! individual cry/als & ! k9ds ( m9]als pres5t4 ,! glacial drift 9 ,ill9ois conta9s _m pieces ( igne\s & metamorphic rocks1 b mo/ ( ! rocks native to ,ill9ois are s$im5t>y4 ,"s s$im5t>y rocks are made up ( wea!r$ fragm5ts ( o!r rocks t h be5 mov$ by riv]s1 waves1 w9ds1 or glaci]s4 ,^! s$im5ts h be5 deposit$ & lat] compact$ or cem5t$ by ! m9]al matt] c>ri$ 9 wat] mov+ ?r\gh !m4 ,su* s$im5t>y rocks are call$ cla/ic 7mean+ brok5 pieces7 rocks1 z oppos$ to ^? =m$ by *emical precipitation f wat] & ^? t consi/ ( fossil rema9s4 ,cla/ic s$im5t>y rocks are classifi$ fir/ on ! basis ( ! size ( ! gra9s ( gravel1 s&1 silt1 & clay ( :i* !y are compos$2 on ! type ( deposition1 su* z glacial drift & w9d-bl[n silt or loess1 t produc$ !m2 & !n on ! basis ( _! m9]al composition4 ,rocks su* z gypsum & "s ( our lime/ones 7 =m$ by *emical precipitation f sea wat]4 ,metamorphic rock lit]ally means rock t has *ang$ =m4 ,! *ange ( =m has be5 caus$ by heat & pressures t occur bel[ ! surface ( ! e>? or by heat f upw>d mov+ hot magmas or melt$ rocks4 ,examples ( metamorphic rocks are f\nd 9 ,ill9ois z b\ld]s & pebbles 9 ! glacial drift4 ,descriptions ( ! rocks & m9]als repres5t$ by specim5s 9 ! ,geological ,survey's rock & m9]al sets foll[4 ,! numb]s prec$+ ! descriptions correspond to ! numb]s on ! specim5s 9 ! sets4 ,al?\gh ! set includes ! rocks & m9]als t are mo/ commonly f\nd 9 ,ill9ois1 _m o!rs c be collect$4 ,= t reason1 foll[+ ! descriptions is a key = id5tify+ o!r ,ill9ois m9]als & rocks4 ,z a fur!r aid to ! beg9n] & ! amateur1 a li/ ( equipm5t useful 9 mak+ a rock & m9]al collection is giv5 at ! end ( ! book4 ,,granite 7#a7 ,,granite is "o ( ! mo/ widespread intrusive 7orig9at+ deep )9 ! e>?7 igne\s rocks4 ,x consi/s *iefly ( feldsp> & qu>tz ) small am\nts ( biotite1 muscovite1 or hornbl5de4 ,mo/ granite is light color$1 b x c be :ite1 gray1 yell[1 p9k1 or deep r$4 ,! texture ranges f m$ium gra9$ to co>se gra9$4 ,granite pebbles or b\ld]s are ! mo/ common igne\s rocks f\nd 9 glacial deposits 9 ,ill9ois4 ,!y are n native to ! /ate b 7 br\ght "h by ! great ice %eets or glaci]s t advanc$ f s\!rn ,canada to cov] mu* ( nor!rn ,unit$ ,/ates dur+ ,plei/oc5e "t4 ,native granitic rock probably lies v deep b5ea? ! entire /ate4 ,x has be5 f\nd 9 deep oil-te/ drill+s along ! we/]n & nor!rn m>g9s ( ,ill9ois4 ,,gabbro 7#b7 ,,gabbro is ano!r intrusive igne\s rock1 b x is heavi] & d>k] ?an granite4 ,x is compos$ ma9ly ( feldsp> & d>k iron-be>+ m9]als t give ! rock a d>k color4 ,x is co>se gra9$ & conta9s little or no qu>tz4 ,m9]al cry/als ( gabbro are especially tightly int]lock$1 mak+ ! rock v difficult to break4 ,wea!r$ gabbro is a ru/y color on ! surface1 because ! iron 9 gabbro *anges color j z a piece ( metallic iron becomes coat$ ) ru/ :5 left out ( doors4 ,l o!r igne\s rocks f\nd ne> ! surface 9 ,ill9ois1 gabbro 0 c>ri$ into ,ill9ois by ! glaci]s & deposit$ z glacial debris4 ,,porphyry 7#c7 ,,porphyry is an igne\s rock id5tifi$ by its texture r ?an its m9]al cont5t1 :i* is v>iable4 ,di/9ct cry/als 7ph5ocry/s7 ( m9]als are emb$d$ 9 a matrix ( f9e-gra9$ rock4 ,! ph5ocry/s =m$ be=e ! ma9 mass ( ! rock h>d5$4 ,any igne\s rock may h a porphyritic v>iety1 su* z granite porphyry & rhyolite porphyry1 al?\gh porphyries are mo/ likely to =m 9 association ) f9e-gra9$ igne\s rocks4 ,porphyry is f\nd 9 ,ill9ois only 9 glacial drift4 ,,basalt 7#d7 ,,basalt is ! mo/ widely di/ribut$ volcanic rock4 ,pyrox5e1 feldsp>1 magnetite 7an iron ore71 & 9 "s in/ances oliv9e1 biotite1 & hornbl5de1 compose ?is rock4 ,! d>k gre51 gray1 or black color is due to ! d>k-color$ m9]als t make up mu* ( ! rock4 ,! m9]als 9 basalt are f9e gra9$ & are pack$ closely toge!r4 ,ph5ocry/s ( oliv9e1 pyrox5e1 & hornbl5de may be pres5t4 ,basalt is easily id5tifi$ by its color & f9e-gra9$ texture4 ,! glaci]s br\ght basalt into ,ill9ois along ) o!r igne\s rocks4 ,,p]idotite 7#e7 ,,p]idotite is ! only igne\s rock native to ,ill9ois t crops out at ! surface4 ,x is f\nd z dikes 7irregul> ve9s7 or sills 7?9 %eets7 t 7 =m$ :5 molt5 rock f deep] 9 ! e>? intrud$ into cracks & fissures 9 ! b$rock ( s\!a/]n ,ill9ois 7,h>d91 ,pope1 ,gallat91 & ,sal9e ,c\nties74 ,p]idotite pebbles & b\ld]s also may be f\nd 9 ! glacial drift4 ,p]idotite ranges f v f9e gra9$ to m$ium gra9$ & has an ev5 texture4 ,x is d>k gray to gre5i% gray1 dep5d+ on ! m9]als pres5t4 ,9 g5]al x is compos$ ( oliv9e1 hornbl5de1 pyrox5e1 & mica1 ) little or no feldsp> or qu>tz4 ,,gneiss ,,& ,,s*i/ 7#f7 ,,gneiss is a metamorphic rock compos$ ( r\ghly p>allel b&s ( m9]als4 ,x is m$ium gra9$ to co>se gra9$ & is g5]ally light 9 color4 ,! names giv5 to gneiss emphasize a di/9ctive texture or m9]al or indicate composition4 ,= example1 biotite gneiss emphasizes a m9]al1 & granite gneiss indicates ! composition ( ! rock4 ,,s*i/ is mu* l gneiss b is f9e gra9$ & has a ?9ly lay]$ /ructure t makes ! rock break ) a wavy surface4 ,"s common types ( s*i/ose rocks are talc s*i/1 *lorite s*i/1 & hornbl5de s*i/4 ,z ! names indicate1 !y are *>act]iz$ by _! dom9ant m9]al4 ,mica s*i/ may be =m$ by ! metamorphism ( ei!r s$im5t>y or igne\s rocks4 ,gneiss & s*i/ are n native to ,ill9ois b are f\nd 9 ! glacial drift4 ,,conglom]ate 7#g7 ,,conglom]ate is a s$im5t>y rock made up ( pebbles or o!r rock fragm5ts cem5t$ 9 a backgr\nd or matrix ( f9] mat]ial1 g5]ally silica1 calcium c>bonate1 clay1 iron oxide1 or a mixture ( ^! sub/ances4 ,! r\nd$ rock fragm5ts h be5 worn by be+ roll$ 9 /reams & along bea*es4 ,illu/ration3 uncaption$ ,if ! pebbles emb$d$ 9 ! matrix are %>p & angul>1 fre%ly brok5 & n worn1 ! rock is call$ breccia & is g5]ally f\nd ne> ! place :]e ! fragm5ts orig9at$4 ,conglom]ate or breccia may be made up ( any type ( rock or m9]al1 mo/ commonly durable mat]ial su* z *]t1 qu>tz1 qu>tzite1 granite1 & gneiss4 ,9 ,ill9ois1 conglom]ates commonly are f\nd at ! base ( s&/one =mations & z b$s 9 ! l[] 8,coal ,measures40 ,!y also are f\nd 9 "s gravel deposits4 ,,s&/one 7#h7 ,,s&/one is a cla/ic s$im5t>y rock consi/+ ( s&-siz$ gra9s 7"o sixty-f\r? to "o-sixte5? in* 9 diamet]7 held toge!r by a cem5t+ mat]ial4 ,z s&/ones become f9] gra9$ !y grade into silt/ones2 z !y become co>s] gra9$ !y grade into conglom]ate4 ,! %ape ( s& gra9s 9 s&/ones ranges f r\nd$ to angul>4 ,qu>tz is ! dom9ant m9]al 9 s&/one1 b o!r rock gra9s & m9]al gra9s 7especially *alc$ony1 feldsp>1 muscovite1 hornbl5de1 magnetite1 or g>net7 g5]ally are pres5t4 ,s&/ones are commonly cem5t$ by c>bonates1 silica1 iron oxides1 or clays4 ,mo/ s&/ones are a %ade ( gray or br[n1 b ! color may v>y f gray or :ite to yell[1 br[n1 or r$4 ,! color probably dep5ds on ! type ( cem5t1 ! am\nt ( organic mat]ial pres5t1 & ! am\nt & degree ( oxidation ( iron 9 ! rock4 ,durability ( s&/ones dep5ds l>gely on ! "* ( ! cem5t4 ,"s s&/ones crumble easily1 b o!rs1 especially ^? cem5t$ by iron oxides or silica1 are t\gh & durable4 ,s&/ones break ar\nd ! gra9s1 giv+ ! brok5 surface a granul> appe>ance4 ,s&/one crops out 9 _m places ?r\gh\t mu* ( ! /ate4 ,9 ,la,salle & ,ogle ,c\nties1 l>ge tonnages ( s& are m9$ f ! ,/4 ,pet] ,s&/one & sold = a v>iety ( uses1 includ+ abrasive s&1 mold+ s&1 & s& = mak+ glass4 ,9 extreme s\!rn ,ill9ois attractively color$ s&/ones h be5 qu>ri$ = build+ /one4 ,,qu>tzite 7#i7 ,,qu>tzite is a metamorphic rock t orig9ally 0 qu>tz s&/one4 ,qu>tzites are produc$ by int5se heat &_/or pressure1 probably aid$ by hot silica-be>+ solutions4 ,! qu>tz gra9s may be s closely int]lock$ t individual gra9s are no long] recognizable4 ,! rock fractures con*oidally ?r\gh bo? ! gra9s & cem5t1 s ! brok5 surface1 unlike t ( s&/one1 is smoo? & may ev5 be glassy l qu>tz4 ,color dep5ds ^u ! am\nt & k9d ( impurities pres5t4 ,a qu>tzite t is all qu>tz is :ite or gray1 b iron or o!r elem5ts may *ange ! color to %ades ( purple1 yell[1 br[n1 or r$4 ,qu>tzite is a v resi/ant1 h>d rock & _c be scrat*$ by a knife4 ,qu>tzite is abundant z b\ld]s & pebbles 9 glacial drift ( ,ill9ois1 hav+ be5 br\ght into ! /ate dur+ ! 8,ice ,age40 ,,%ale 7#aj7 ,,%ale is a common & important s$im5t>y rock compos$ ( compact$ clay or mud4 ,x is s f9e gra9$ t ! m9]als =m+ x g5]ally _c be id5tifi$ )\t ! aid ( ,x-ray4 ,%ales are compos$ ma9ly ( clay m9]als b1 l o!r s$im5t>y rocks1 g5]ally include o!r m9]als4 ,%ales conta9+ calcium c>bonate are call$ calc>e\s %ales4 ,mo/ %ales conta9 silt or s& p>ticles2 if silt or s& is pres5t 9 l>ge quantity1 ! rock is call$ silty %ale or s&y %ale4 ,if mica m9]als are pres5t 9 quantity 9 a %ale x is call$ micace\s %ale4 ,! p>ticles ( mo/ clay m9]als are ?9 & flat & ov]lap ea* o!r4 ,%ales h a wide range ( colors b mo/ ( ^? 9 ,ill9ois are gray4 ,a gray1 black1 or blue-gray color is caus$ by organic matt] 9 ! %ale2 %ades ( r$1 br[n1 yell[1 or gre5 are caus$ by iron comp\nds4 ,%ale is widely di/ribut$ 9 ,ill9ois1 especially 9 8,coal ,measures0 rocks1 & is us$ 9 manufactur+ bricks1 dra9 tile1 build+ tile1 & lightweight aggregate4 ,,clay 7#aa7 ,,clay is an unconsolidat$ rock made up ( a gr\p ( hydr\s alum9um silicate m9]als1 ( :i* *lorite1 montmorillonite1 kaol9ite1 & illite are ! mo/ abundant4 ,^! m9]als are =m$ by ! wea!r+ or alt]ation ( o!r rocks & m9]als4 ,clays are v f9e gra9$ & _! m9]als h t9y1 flat cry/als t c be di/+ui%$ f ea* o!r only by laboratory me?ods4 ,al?\gh clays may appe> to be simil>1 _! compositions v>y greatly4 ,"s clays are :ite1 b mo/ are color$ by iron comp\nds & organic matt]4 ,wet clays h an e>?y odor & g5]ally are slick & pla/ic1 b dry clays are relatively h>d & are greasy to ! t\*4 ,clays are abundant 9 ,ill9ois1 especially 9 soils1 9 %ales1 & z clay deposits4 ,9 ,ill9ois ! und]clays t occur b5ea? coal b$s are p>ticul>ly well suit$ to ! manufacture ( bricks1 pott]y1 /onew>e1 & dra9 tile4 ,,lime/one 7#ab7 ,,lime/one is a s$im5t>y rock compos$ ( p>ticles ( calcite 7calcium c>bonate74 ,! cry/als may range f f9e to co>se4 ,_m lime/ones conta9 o!r m9]als1 su* z *]t1 clay1 or s&1 & 9 "s places !y grade into dolomite 7calcium magnesium c>bonate74 ,_m lime/ones are :ite or gray4 ,yell[ or br[n %ades are caus$ by iron oxide impurities & d>k gray to black colors by organic matt]4 ,lime/ones =m 9 v>i\s ways4 ,"s are deposit$ :5 calcium c>bonate precipitates f solution2 o!rs are =m$ :5 ! %ells or skeletons ( organisms su* z bra*iopods1 clams1 & corals accumulate on a sea floor4 ,if su* fossils are v abundant1 ! rock is call$ fossilif]\s lime/one4 ,lime/one compos$ ( t9y1 r\nd$ concretions is call$ oolite or oolitic lime/one4 ,lime/one eff]vesces freely 9 dilute hydro*loric acid1 b dolomite mu/ be p[d]$ be=e x w eff]vesce4 ,9 nature1 lime/ones may be dissolv$ by p]colat+ wat] conta9+ weak acid 7su* z c>bonic acid1 compos$ ( wat] & c>bon dioxide74 ,at _m places 9 s\!rn & s\?we/]n ,ill9ois su* solution ( lime/ones has produc$ caves & cav]ns4 ,lime/one outcrops are abundant 9 ,ill9ois1 especially along ! bluffs ( ! ,mississippi1 ,ohio1 & ,ill9ois ,riv]s4 ,lime/one has _m uses4 ,x is us$ = build+ /one1 road surfac+1 railroad balla/1 9 ! manufacture ( portl& cem5t1 &1 if ( high purity1 = mak+ lime & *emicals & z a flux 9 smelt+ metals4 ,x also is us$1 z agricultural lime/one1 to add calcium to ! soil4 ,,peat 7#ac7 ,,peat is produc$ by ! p>tial decomposition ( plants t accumulate1 ) v>y+ am\nts ( m9]al matt]1 9 old ponds1 swamps1 & lakes1 & 9 ab&on$ *annels 9 valley bottoms along _m riv]s & /reams4 ,peat may be an e>ly /age 9 ! =mation ( coal4 ,peat ranges f light to d>k br[n1 ! color1 decomposition1 & compaction increas+ ) dep? 9 ! deposit4 ,"s ( ! plant rema9s are cle>ly di/+ui%able & appe> z fibr\s fragm5ts held toge!r by ! f9e peat p>ticles4 ,! type ( peat common 9 ,ill9ois has a high wat] cont5t4 ,be=e x is dri$ x is s(t & spongy to ! t\*2 ^u dry+1 x loses mu* wat] & becomes h>d]4 ,peat is us$ z a fuel 9 "s p>ts ( ! _w1 b its heat+ value is l[ comp>$ to t ( coal4 ,x burns ) a long flame & leaves a great deal ( a% because ( ! silt & s& t 7 buri$ ) ! vegetation4 ,peat & peat moss are us$ *iefly z an absorb5t1 z /able litt]1 z insulat+ & pack+ mat]ial1 & by g>d5]s to increase ! wat]-hold+ capacity ( soils4 ,peat is f\nd 9 _m places 9 ,ill9ois b ! l>ge/ deposits are 9 nor!a/]n ,ill9ois4 ,,coal 7#ad7 ,,coal1 an organic /ratifi$ rock1 is =m$ f accumulat$ plant mat]ial & p>tially decay$ plants t 7 buri$ dur+ ! 8,coal ,measures0 p]iod 9 ,ill9ois m ?an #bjj million ye>s ago4 ,s$im5ts deposit$ ov] ! peat-l organic mat]ial compact$ x4 ,*emical *anges gradually took place & result$ 9 ! loss ( wat] & gases1 leav+ a high] p]c5tage ( c>bon ?an ! orig9al mat]ial conta9$4 ,! am\nt ( su* *ange t has tak5 place det]m9es ! rank ( ! coal4 ,! l[e/ ranks are call$ lignite1 ! int]m$iate gr\p is call$ bitum9\s 7s(t7 coal1 & coals ( ! highe/ rank1 ) ! highe/ c>bon cont5t1 are call$ an?racite 7h>d coal74 ,m9]al matt]1 su* z %ale1 clay1 or pyrite1 g5]ally is pres5t 9 ! coal & becomes a% :5 ! coal is burn$4 ,mo/ coal m9$ 9 ! ,unit$ ,/ates is bitum9\s coal4 ,x is black1 brittle1 breaks into angul> blocks1 has a %9y lu/]1 & g5]ally %[s a b&$ /ructure4 ,coal m9+ is an important indu/ry 9 ,ill9ois1 & ! /ate conta9s ! l>ge/ kn[n res]ves ( bitum9\s coal 9 ! ,unit$ ,/ates4 ,m9able coal b$s und]lie ab\t two-?irds ( ! /ate4 ,z _m z #bj diff]5t coal b$s h be5 m9$ 9 ,ill9ois1 ! mo/ important be+ ! ,h]r9 7,no4 #f7 & ! ,spr+field 7,no4 #e7 or ,h>risburg 7,no4 #e74 ,! coal 9 mo/ m9+ areas av]ages #e to #g feet ?ick & 9 places atta9s a ?ickness ( #ae feet4 ,9 und]gr\nd m9es ! coal is approa*$ by v]tical or incl9$ %afts4 ,9 op5 cut1 or /rip1 m9es all ( ! ov]ly+ mat]ial 7ov]burd57 is remov$1 leav+ ! coal expos$4 ,coal z mu* z #ajj feet deep is n[ be+ /rip m9$ 9 ,ill9ois4 ,ill9ois coal is n[ us$ ma9ly = g5]at+ electric p[]1 = indu/rial purposes1 & = heat+4 ,9 indu/ry1 coal is us$ ext5sively = p[]1 heat+1 burn+ cem5t1 fir+ clay products su* z brick1 tile1 pott]y1 porcela91 & *9a1 & mak+ coke4 ,c]ta9 ,ill9ois coals :5 mix$ ) coal f ! ea/]n "p ( ! ,unit$ ,/ates1 produce metallurgical coke = mak+ /eel4 ,gases1 oils1 & t>s d]iv$ 9 process+ coal = coke h be5 us$ = mak+ _m *emical products1 includ+ dyes1 p]fumes1 explosives1 m$ic9es1 insecticides1 pla/ics1 & road t>4 ,,petroleum 7#ae7 ,,petroleum 7crude oil7 is class$ z a m9]al res\rce al?\gh x is a liquid hydroc>bon & n te*nically a m9]al or rock4 ,x is1 h[ev]1 f\nd 9 ! pores & fractures ( rocks4 ,! color ( crude oil ranges f yell[ ?r\gh gre5 & br[n to black4 ,illu/ration3 uncaption$ ,ar* 7anticl9e7 ,gas ,por\s rock ,nonpor\s rock ,oil saturat$ rock ,wat] ,break 7fault7 ,nonpor\s rock ,oil saturat$ por\s rock ,wat] saturat$ por\s rock ,trap =m$ by *ange 9 "* ( rock ,wat] ,nonpor\s rock ,por\s rock ,petroleum _h its orig9 9 ! plants & animals buri$ 9 anci5t s$im5ts4 ,! organic matt] *ang$ sl[ly into ! complex mixture ( hydrog5 & c>bon comp\nds t is petroleum4 ,because gas is light] ?an oil1 & oil 9 turn light] ?an wat]1 gas & oil move upw>d 9 a por\s rock conta9+ all ?ree4 ,gas moves to ! highe/ position ) oil next bel[ & wat] 9 ! l[e/ "p ( ! rock4 ,oil pools exi/ :]e geologic b>ri]s h /opp$ ! movem5t ( gas & oil4 ,ar*es 7upw>d folds or anticl9es71 breaks 7faults71 & lat]al *anges f por\s to nonpor\s rock are geologic features t s]ve to localize oil pools )9 ! res]voir rock4 ,petroleum is obta9$ by drill+ wells into ! res]voir rock4 ,gas t is free or dissolv$ 9 ! petroleum exp&s z pressure is releas$ :5 ! well is drill$ & drives ! oil to ! well4 ,wat] 9 ! res]voir rock also acts z a driv+ =ce4 ,:5 ?is natural pressure is no long] effective1 o!r me?ods 7second>y recov]y7 are us$ to recov] ! oil rema9+ 9 ! res]voir4 ,por\s s&/ones & lime/ones are ! oil-be>+ rocks4 ,ill9ois also has deposits ( oil %ale f :i* petroleum may be produc$ 9 ! future4 ,?\s&s ( products are d]iv$ f petroleum1 includ+ gasol9e1 k]os5e1 naph?a1 lubricat+ oils & waxes1 m$ic9al oils1 salves1 heavy fuels1 road oils1 t>1 & asphalt4 ,,glaciat$ ,,pebbles 7#af7 ,,glaciat$ ,,pebbles are small /ones ^: %apes h be5 alt]$ by ! gr9d+ action ( a glaci]4 ,su* pebbles commonly h at lea/ "o flatt5$ side t %[s scrat*es 7call$ /riae74 ,! /riae 7 produc$ :5 ! pebbles 7 pu%$ ov] b$rock or gr\nd aga9/ o!r pieces ( rock4 ,glaci]s tore fragm5ts f ! b$rock ov] :i* !y mov$ & ! fragm5ts accumulat$ 91 on1 & "u ! mass ( ice4 ,! rock fragm5ts 7 transport$1 "s ( !m f> f _! s\rce1 & 7 deposit$ z ! glaci] mov$ along or :5 ! ice melt$4 ,s(t rocks l lime/one & dolomite are easily scrat*$1 b s(t rocks _c make grooves 9 h>d igne\s & metamorphic rocks4 ,!re=e s(t rocks h m /riae4 ,glaciat$ pebbles c be f\nd 9 deposits 9 _m p>ts ( ! /ate1 especially 9 nor!a/]n & ea/-c5tral ,ill9ois4 ,h[ev]1 _m deposits ne> ! surface h be5 wea!r$ & /riae h be5 de/roy$4 ,an especially good place to look = /riat$ pebbles is 9 qu>ries & /rip m9es :]e glacial drift ov]burd5 has be5 remov$4 ,pebbles f\nd 9 su* deposits %[ good /riae = !y are b little wea!r$4 ,,silica ,,s& 7#ag7 ,,silica ,,s& is ! comm]cial "n = s& compos$ almo/ entirely ( gra9s ( qu>tz4 ,s& ( ?is k9d is m9$ 9 ,ill9ois f ! ,/4 ,pet] ,s&/one 9 ,la,salle & ,ogle ,c\nties4 ,! co>s] gra9s ( ! s& are *>act]i/ically r\nd$ & fro/$4 ,! fro/+ causes ! s& to look :ite4 ,ill9ois silica s& has _m uses4 ,x is us$ j z x is m9$ = mold+ s& 9 :i* metal ca/+s are made1 = l9+ indu/rial furnaces1 & = _m o!r purposes4 ,"s ( ! s& is wa%$ to remove ! small am\nt ( impurities pres5t4 ,! wa%$ s& is us$ = su* purposes z mak+ glass1 = gr9d+ plate glass smoo?1 = s& bla/+1 = mold+ metal1 z fractur+ s& to increase ! production ( oil wells4 ,"s silica s& is gr\nd to a f9e p[d] & us$ z a f9e abrasive1 z a fill] 9 pa9t1 & z an +r$i5t 9 pott]y1 glazes1 & enamel4 ,a specially prep>$ ,/4 ,pet] s&1 kn[n ?r\gh\t ! _w z ,/&>d ,ottawa ,te/+ ,s&1 is us$ to te/ ! /r5g? ( cem5ts & z a laboratory /&>d 9 physical te/s ( o!r s&s4 ,,mold+ ,,s& 7#ah7 ,,mold+ ,,s& is a mixture ( s& & clay or o!r bond+ mat]ial & is us$ to make molds 9 :i* metal is ca/ into v>i\s useful %apes4 ,!re are two k9ds ( mold+ s&s1 syn!tic & natural bond$4 ,! fir/ is an artificial mixture ( silica s& & clay2 ! second is a naturally occurr+ mixture ( s& & a bond+ mat]ial4 ,= ca/+1 mold+ s& is fir/ moi/5$ ) wat] & %ap$ into a mold ( ! metal "p to be reproduc$4 ,! mold is !n all[$ to dry & ! molt5 metal p\r$ into x4 ,! bond+ mat]ial 9 ! s& mu/ be /rong en\gh to keep ! mold 9 %ape dur+ ^! op]ations4 ,natural bond$ mold+ s& is produc$ 9 ,fayette1 ,bond1 ,bureau1 ,c>roll1 ,kankakee1 & ,rock ,isl& ,c\nties1 ,ill9ois4 ,,tripoli 7#ai7 ,,tripoli1 call$ amorph\s silica 9 s\!rn ,ill9ois1 is a :ite or light br[n1 p[d]y sub/ance t rubs (f on ! h&s l *alk4 ,x consi/s mo/ly ( v small p>ticles ( qu>tz t result f ! wea!r+ ( calc>e\s *]t or highly silice\s lime/one4 ,x is f9ely gr\nd & us$ z 8:ite r\ge0 = poli%+ optical l5ses1 z a fill] 9 pa9ts1 9 mak+ c]amic products1 z a compon5t ( buff+ comp\nds1 & z a f9e abrasive4 ,tripoli occurs 9 ,alex&] & ,union ,c\nties & is mill$ at ,elco & ,tamms 9 ,alex&] ,c\nty4 ,,full]',s ,,e>? 7#bj7 ,,full]',s ,,e>? is clay or silty clay mat]ial t conta9s v f9e silica4 ,x is s(t1 nonpla/ic1 opaque1 has a greasy feel :5 wet1 & does n readily break up 9 wat]4 ,its color v>ies f blue-gray to yell[ or buff4 ,full]'s e>? is valuable = its unique prop]ty ( absorb+ & decoloriz+ sub/ances4 ,! mat]ial 0 fir/ us$ to 8full0 or remove grease f wool5 clo?1 h5ce its "n4 ,x also has be5 us$ to filt] & blea* m9]al & vegetable oils by absorb+ d>k organic matt]4 ,9 ,pulaski ,c\nty 9 extreme s\!rn ,ill9ois ! ,port]'s ,creek ,=mation conta9s deposits ( clay t 7 at "o "t ! s\rce ( full]'s e>? & /ill af=d clay ^: absorb5t prop]ties make x useful z litt] & z sweep+ & clean+ comp\nd4 ,,qu>tz 7#ba7 ,,qu>tz is ! mo/ common ( all m9]als1 mak+ up ab\t #ab p]c5t ( ! e>?'s cru/4 ,!re are two ma9 types ( qu>tz--cry/all9e qu>tz & d5se1 crypto-cry/all9e 7submicroscopic7 qu>tz4 ,_m d5se v>ieties occur 9 ,ill9ois1 probably ! mo/ common are *]t or fl9t4 ,illu/ration3 uncaption$ ,cry/als ( qu>tz are typically six-sid$1 elongat$1 h %>ply po9t$ pyramid-l ends1 & are apt to gr[ toge!r =m+ tw9s4 ,good cry/als are r>e 9 ,ill9ois1 & ! cry/al /ructure is n app>5t 9 ! commonly occurr+ gra9s & masses4 ,qu>tz is brittle & h>d4 ,x may be colorless or t9t$1 transp>5t or transluc5t1 b m commonly x is :ite & ne>ly opaque4 ,transp>5t qu>tz looks mu* l ord9>y glass1 b x scrat*es glass easily4 ,x has a glassy to brilliant lu/] & breaks irregul>ly or ) a good con*oidal fracture4 ,"s v>ieties ( qu>tz t are us$ = semipreci\s gems are *alc$ony1 agate1 onyx1 & jasp]4 ,*alc$ony is waxy1 smoo?1 g5]ally transluc5t1 :ite to gray1 blue1 br[n1 or black4 ,agate is a =m ( *alc$ony t has a mottl$ or v>iegat$ b&$ appe>ance & may be yell[1 gre51 r$1 br[n1 blue1 gray1 or black4 ,onyx is agate ) p>allel b&s t z a rule are br[n & :ite or black & :ite4 ,jasp]1 an impure opaque qu>tz1 g5]ally is r$4 ,qu>tz occurs z rock cry/al 7colorless1 transp>5t71 milky qu>tz 7:ite1 ne>ly opaque71 & smoky qu>tz 7smoky yell[ to gray or br[n7 9 geodes f ! ,w>saw & ,keokuk ,lime/ones ( ! ,nauvoo-,hamilton-,w>saw area & z ve9 & cavity fill+s associat$ locally ) fluorite1 sphal]ite1 & gal5a 9 extreme s\!rn ,ill9ois4 ,x also occurs z vug 7cavity7 fill+s 9 lime/ones & s&/ones4 ,,feldsp> 7#bb7 ,,feldsp> is ! "n appli$ to a gr\p ( m9]als t are ! second mo/ common ( all ! e>?'s m9]als4 ,all feldsp>s are compos$ ( alum9um1 silicon1 & oxyg51 comb9$ ) v>y+ am\nts ( "o or m metals1 p>ticul>ly potassium1 sodium1 calcium1 & li?ium4 ,! m9]als are h>d1 h a smoo? glassy or pe>ly lu/]1 & cleave along two planes ne>ly at "r angles to ea* o!r4 ,feldsp>s are fairly light weight4 ,! /reak is :ite1 b ! color ( ! m9]al is highly v>iable1 al?\gh potassium & sodium-be>+ feldsp> are commonly :ite or p9k & mo/ plagioclase feldsp> is gray4 ,feldsp>s are ess5tial p>ts ( ! cry/all9e igne\s rocks4 ,_! decomposition products are pres5t 9 mo/ soils4 ,9 ,ill9ois relatively small feldsp> cry/als c be f\nd associat$ ) qu>tz & o!r m9]als 9 granite & gneiss b\ld]s & pebbles 9 glacial drift4 ,,mica 7#bc7 ,,mica is ! "n ( a family ( complex alum9um silicate m9]als t c be split easily into pap]-?91 flexible %eets4 ,if brok5 across ! gra9 at "r angles to ! flat1 smoo? surface !y fracture ragg$ly4 ,9 a s+le mica cry/al ! %eets range f m or less transp>5t to transluc5t & are arrang$ "o on top ( ano!r l a deck ( c>ds4 ,micas are t\gh & some:at ela/ic1 s(t en\gh to be split & scrat*$ by a f+]nail1 & are light weight4 ,!y h a nonmetallic1 glassy or pe>ly lu/]1 al?\gh yell[ mica may appe> to be metallic4 ,color & /reak dep5d ^u ! *emical composition ( ! m9]al4 ,muscovite1 or :ite mica1 conta9s potassium & makes a colorless or :ite /reak4 ,biotite1 or black mica1 conta9s iron & magnesium & is commonly d>k gre5 or black1 al?\gh x may be %ades ( yell[ or br[n2 its /reak is uncolor$4 ,mica is abundant z t9y1 %imm]+ flakes 9 ,ill9ois s&s1 s&/ones1 & %ales 7:i* are !n said to be micace\s74 ,x also is common 9 _m v>ieties ( igne\s & metamorphic rocks4 ,:ite or yell[ flakes may %[ a brilliant lu/] & may be mi/ak5 = silv]1 plat9um1 or gold1 b ^? m9]als are heavy & malleable :]eas mica is n4 ,,calcite 7#bd7 ,,calcite1 a common rock-=m+ m9]al1 consi/s ( calcium c>bonate4 ,! m9]al is :ite or colorless1 b impurities may t9t x %ades ( yell[ or gray4 ,transp>5t calcite is m r>e ?an ! t9t$ v>ieties4 ,transp>5t calcite possesses ! prop]ty ( d\ble refraction2 an image appe>s d\ble :5 view$ ?r\gh a calcite cleavage block4 ,calcite has a glassy lu/]1 its /reak is :ite or colorless4 ,! m9]al is ( m$ium h>dness & c be scrat*$ by a p5ny or a piece ( w9d[ glass b n by ! f+]nail4 ,x is fairly light weight & eff]vesces freely 9 cold dilute hydro*loric acid4 ,illu/ration3 uncaption$ ,calcite has a v>iety ( cry/al =ms b 9 ,ill9ois flatt5$ block-%ap$ cry/als & elongate cry/als ) tap]+ po9ts 78dogtoo? sp>07 are ! mo/ common4 ,:5 brok51 calcite cleaves into six-sid$ blocks call$ rhombs4 ,cry/als ( calcite are f\nd 9 ,ill9ois z l9+s 9 geodes 9 c]ta9 lime/ones & %ales1 especially 9 ! ,nauvoo-,hamilton-,w>saw area1 & z cry/all9e masses 9 lime/one & dolomite4 ,small am\nts ( cle> cry/all9e calcite are associat$ ) v>i\s ores 9 nor?we/]n & extreme s\!rn ,ill9ois4 ,calcite is ! pr9cipal m9]al 9 lime/ones & occurs z a compon5t ( _m concretions4 ,,fluorite 7#be7 ,,fluorite1 or fluorsp>1 is made up ( ! elem5ts calcium & fluor9e4 ,! m9]al is easily id5tifi$ by its p]fect cleavage1 color1 & h>dness4 ,x occurs 9 cubic cry/als t may be tw9n$ b is m (t5 f\nd z irregul> masses4 ,x c be split into diamond-%ap$1 eight-sid$ =ms 7octah$rons74 ,fluorite is commonly gray1 :ite1 or colorless1 b x may be gre51 blue1 purple1 p9k1 or yell[4 ,! /reak is colorless & ! lu/] glassy4 ,x c be scrat*$ by a knife or a piece ( w9d[ glass1 is fairly light weight1 & is transp>5t to transluc5t4 ,ext5sive deposits ( fluorite1 "o ( ,ill9ois' important comm]cial m9]als1 occur 9 ,h>d9 & ,pope ,c\nties 9 extreme s\!rn ,ill9ois1 :]e x is associat$ ) gal5a1 sphal]ite1 calcite1 b>ite1 & o!r less abundant m9]als4 ,fluorite is us$ to make hydr(luoric acid1 to =m a fluid slag 9 ! production ( iron & /eel1 9 ! manufacture ( alum9um1 to make _m *emical products1 & 9 ! c]amic indu/ry1 9 :i* x is us$ to make color$ glass1 enamels1 & glazes4 ,,gypsum 7#bf7 ,,gypsum1 hydr\s calcium sulfate1 is a colorless1 transp>5t to transluc5t m9]al :5 pure1 b x (t5 is /a9$ yell[ by impurities4 ,x has a :ite /reak1 is s(t en\gh to be scrat*$ by a f+]nail1 & is light weight4 ,illu/ration3 uncaption$ ,gypsum occurs 9 sev]al =ms4 ,sel5ite is a co>sely cry/all9e1 transp>5t v>iety1 compos$ ( flat1 ne>ly diamond-%ap$ cry/als t c be split easily into ?9 %eets1 h a glassy lu/]1 & (t5 gr[ toge!r to =m 8fi%tail tw9s40 ,cry/als ( sel5ite occur 9 %ales ( ! 8,coal ,measures0 ( s\!rn1 nor?-c5tral1 & we/]n ,ill9ois1 & c be pick$ up at ! surface4 ,sat9 sp> has cry/als l silky ?reads closely pack$ toge!r1 splits p>allel to ! fib]s1 & is f\nd z fill+s 9 rock cracks & z ?9 lay]s 9 %ales4 ,massive gypsum is granul>4 ,gypsum deposits occur deep und]gr\nd 9 ,ill9ois b ?us f> h n be5 m9$4 ,,*]t 7#bg7 ,,*]t1 "o ( ! ma9 =ms ( silicon dioxide1 is cryptocry/all9e 7submicroscopic7 qu>tz4 ,mo/ ( ! *]t 9 ,ill9ois is :ite or gray1 b impurities /a9 _m deposits yell[1 br[n1 or ev5 p9k4 ,*]t is s h>d t x c scrat* glass & ord9>y /eel4 ,x is fairly light weight1 d5se1 opaque1 & brittle2 ! lu/] is dull4 ,fl9t1 a v>iety ( *]t1 is g5]ally d>k color$1 m d5se1 may h a glassy lu/] & be transp>5t 9 ?9 flakes4 ,bo? *]t & fl9t h a smoo?1 curv$ 7con*oidal7 fracture1 b fl9t t5ds to break ) ?9n]1 %>p] edges4 ,indians us$ fl9t & *]t to make arr[ po9ts & spe>heads4 ,*]t occurs z r\nd$ masses 7nodules & concretions7 or z irregul> lay]s 9 lime/ones & dolomites 9 nor!rn1 we/]n1 s\?we/]n1 & s\!rn ,ill9ois4 ,because *]t is h>d & m resi/ant to wea!r+ ?an lime/one or dolomite1 x (t5 rema9s aft] ! re/ ( ! rock has wea!r$ away4 ,*]t also is abundant 9 _m glacial deposits because x is h>d & resi/s solution4 ,/reams t fl[ ?r\gh *]ty b$rock or glacial deposits c>ry pebbles along & conc5trate !m z gravel 9 /ream *annels4 ,*]ty /ream gravels are especially abundant 9 we/]n & s\!rn ,ill9ois4 ,br[n *]t gravels 9 ! s\!rn "p ( ! /ate are us$ = road gravel4 ,o!r deposits 9 extreme s\!rn ,ill9ois1 consi/+ ( angul> fragm5ts ( *]t & a small am\nt ( clay 7kn[n locally z novaculite gravel7 also are us$ = road surfac+4 ,:ite & gray *]t occur z massive b$rock deposits sev]al hundr$ feet ?ick 9 ,union & ,alex&] ,c\nties4 ,,pyrite ,,& ,,m>casite 7#bh7 ,,pyrite & ,,m>casite are iron disulfide comp\nds4 ,!y look mu* alike b h diff]5t cry/al =ms4 ,bo? are brittle1 h>d1 brassy yell[ ) metallic lu/]1 & opaque4 ,! be/ di/+ui%+ feature is cry/al %ape4 ,! pyrite cry/als are cubes1 b ! m>casite cry/als are blade- or ne$le-%ap$4 ,pyrite & m>casite h be5 mi/ak5 = gold because !y are yell[ & metallic & h5ce are sometimes ref]r$ to z 8fool's gold04 ,!y1 h[ev]1 are h>d] ?an gold1 t>ni%1 & leave a d>k /reak1 :]eas gold is s(t1 v heavy1 does n t>ni%1 & leaves a yell[ /reak4 ,gold is malleable1 b pyrite or m>casite are r$uc$ to p[d] if !y are p\nd$ & give (f a noticeable odor ( sulfur dioxide gas if !y are heat$4 ,pyrite & m>casite are f\nd 9 _m deposits 9 ,ill9ois4 ,!y occur z gra9s or l>g] masses 9 "s clays1 %ales1 & lime/ones4 ,!y also occur ) ! lead & z9c ores ( nor?we/]n ,ill9ois &1 9 small am\nts1 ) ! fluorite & associat$ m9]als 9 ! extreme s\!rn "p ( ! /ate4 ,bo? pyrite & m>casite are common z surface coat+s1 ve9s1 & concretion>y /ructures 9 coal & 9 d>k %ales associat$ ) coal4 ,!y are ref]r$ to z 8coal brasses0 or 8sulfur0 :5 f\nd z impurities 9 coal4 ,a pot5tial use = pyrite & m>casite is 9 ! manufacture ( sulfuric acid = indu/rial use4 ,coal brasses recov]$ f ,ill9ois coal h be5 s us$4 ,,limonite 7#bi7 ,,limonite is an iron oxide conta9+ wat] & has a complex *emical composition4 ,! limonite f\nd 9 ,ill9ois may be yell[1 orange1 r$1 br[n1 or black1 b its /reak is always yell[i% br[n4 ,! m9]al may h a glassy or an e>?y lu/]4 ,x may be too h>d to be scrat*$ by a knife4 ,x is ( m$ium weight4 ,limonite is common & occurs z concretions & cavity fill+s 9 s$im5t>y rocks1 & z coat+s on !m1 especially s&/one4 ,x also occurs z iron ru/1 z scum on /agnant wat]1 & x accumulates ar\nd rootlets 9 soils4 ,small am\nts color lime/one1 dolomite1 clay1 %ale1 s&/one1 & gravel4 ,"s s&s are firmly cem5t$ by br[n or black limonite & look mu* l iron ore4 ,clays conta9+ a high p]c5tage ( limonite are call$ o*]4 ,9 "s /ates limonite is m9$ z an iron ore1 & 9 ,ill9ois x 0 s us$ 9 ,h>d9 ,c\nty 9 ! middle #ahjj's1 b deposits are n l>ge en\gh = pr(itable use n[4 ,,sphal]ite 7#cj7 ,,sphal]ite1 z9c sulfide1 is a major ore ( z9c4 ,x has a res9\s lu/] & a :ite1 yell[1 or br[n /reak4 ,ill9ois sphal]ite is g5]ally yell[1 yell[i% br[n1 r$di% br[n1 or br[ni% black4 ,x is ( m$ium weight1 brittle1 c be scrat*$ by a piece ( w9d[ glass b n by a p5ny4 ,x is commonly opaque b may be transluc5t on ?9 edges4 ,sphal]ite is m9$ ) gal5a 9 nor?we/]n ,ill9ois & 9 extreme s\!rn ,ill9ois ) gal5a & fluorite4 ,small cry/als occasionally are f\nd 9 lime/ones & z cry/all9e masses 9 clay-iron/one concretions4 ,,gal5a 7#ca7 ,,gal5a1 lead sulfide1 is ! pr9cipal ore ( lead4 ,x is /eel gray1 heavy1 opaque1 & has a bright metallic lu/]1 ?\gh ! %9y surface may be dull$ by a coat+ ( lead c>bonate4 ,x has a gray or black /reak1 is s(t en\gh to m>k pap]1 & c be scrat*$ by a p5ny4 ,! cube-%ap$ cry/als readily break into cubic1 "r-angl$ fragm5ts4 ,probably ! mo/ obvi\s features ( ! m9]al are its bright metallic lu/] on fre% surfaces1 high specific gravity1 & cubic cleavage4 ,illu/ration3 uncaption$ ,at _m places gal5a is arg5tif]\s 7silv]-be>+71 b ,ill9ois gal5a is relatively unimportant = its silv] cont5t4 ,z a s\rce ( lead1 h[ev]1 x is an important comm]cial product ( ! /ate4 ,scatt]$ pieces ( gal5a are f\nd at _m places 9 ,ill9ois4 ,"s occur 9 ! glacial deposits1 o!rs occur z small pockets & z cry/als 9 lime/ones & geodes4 ,9 only two areas ( ! /ate are deposits ( comm]cial value4 ,9 nor?we/]n ,ill9ois gal5a occurs 9 association ) sphal]ite2 9 extreme s\!rn ,ill9ois x occurs 9 association ) fluorite & sphal]ite4 ,,concretions 7#cb7 ,,concretions are conc5trations ( inorganic s$im5t>y mat]ial )9 o!r s$im5ts4 ,m9]als t commonly =m concretions are silica 79 ! =m ( opal1 *]t1 *alc$ony1 & qu>tz71 calcite1 sid]ite1 pyrite1 m>casite1 & limonite4 ,concretions may =m ei!r z ! s$im5t ar\nd !m is =m+ or aft] ! s$im5t ar\nd !m has h>d5$4 ,!y may be =m$ :5 wat] conta9+ dissolv$ m9]als seeps ?r\gh ! s$im5t or rock & leaves a conc5tration ( m9]al matt] 9 a cavity or ar\nd a c5tral p>ticle 7nucleus7 su* z ! rema9s ( a plant or animal4 ,portions ( rock may also become firmly cem5t$ by su* m9]al matt]4 ,concretions range 9 size f m9ute p>ticles to objects sev]al feet 9 diamet]4 ,%apes range f sph]es to tubes4 ,_m are globul> or lumpy-surfac$1 "s are smoo?4 ,because concretions g5]ally are h>d] ?an ! surr\nd+ rock 9 :i* !y h =m$1 !y d n wea!r away z readily & may rema9 aft] ! surr\nd+ mat]ial has be5 erod$4 ,conc5trations ( calcite are f\nd 9 loess deposits4 ,!y may look l biz>re1 knobby figur9es1 & ! ,g]mans call$ !m loess k9d*5 7little *ildr5 ( ! loess74 ,iron/one concretions1 especially common 9 _m ,ill9ois %ales1 are =m$ by a local conc5tration ( ! m9]al sid]ite 7iron c>bonate7 9 ! rock4 ,! concretions f\nd 9 wea!r$ outcrops commonly are p>tly or entirely wea!r$ to limonite4 ,"s iron/one concretions gr[ toge!r into odd %apes4 ,mazon ,creek iron/one concretions ( nor!a/]n ,ill9ois1 _w fam\s = _! fossils1 are sid]itic4 ,! concretions are commonly cov]$ ) limonite1 ! result ( oxidation4 ,limonite concretions1 g5]ally ) a high cont5t ( clay1 silt1 or s&1 occur 9 loess1 %ale1 & s&/one4 ,concretions ( *]t & o!r =ms ( silica are common 9 lime/ones4 ,9 _m places1 because ( _! great] resi/ance to wea!r+1 l5ses & nodules ( *]t protrude f ! b$s4 ,pyrite or m>casite occur z concretions or concretion-l masses 9 "s coal b$s & 9 ! black %ales1 sometimes popul>ly call$ 8slates10 above coal b$s4 ,"s o!r ,p5nsylvanian clays & %ales also conta9 concretions or co>sely cry/all9e aggregates ( ^! m9]als4 ,,geodes 7#cc7 ,,geodes are r\ghly sph]ical bodies t may be fill$ ) lay]s ( m9]als1 l9$ ) cry/als1 or bo?4 ,! out] lay] ( geodes f\nd 9 ,ill9ois z a rule is compos$ ( *alc$ony1 a =m ( f9ely cry/all9e silica4 ,geodes diff] f concretions 9 t !y =m inw>d f ! out] %ell1 :]eas concretions develop outw>d f a c5t]4 ,ev5 if geodes h be5 completely fill$ by m9]al matt]1 _! inw>d-project+ cry/als prove t !y =m$ )9 a cavity4 ,9 a p>tly fill$ cavity1 cry/als g5]ally are well =m$ because !y grew )\t be+ cr[d$4 ,"s ( ! be/ m9]al specim5s kn[n 9 ,ill9ois are f\nd z cry/al l9+s 9 geodes4 ,illu/ration3 uncaption$ ,qu>tz is ! mo/ common m9]al deposit$ 9 geodes1 b calcite1 aragonite1 dolomite1 sid]ite1 pyrite1 gal5a1 fluorite1 & sphal]ite also are f\nd4 ,geodes rang+ 9 size f less ?an "o in* to a foot or m 9 diamet] c be ga!r$ f /reams :]e !y h accumulat$ z residual b\ld]s aft] ! rock 9 :i* !y 7 enclos$ has be5 erod$4 ,holl[ geodes are ! mo/ desirable because !y h bett] cry/als4 ,!y c be di/+ui%$ f solid ones by _! comp>ative lightness ( weight4 ,geodes are commonly associat$ ) lime/one & dolomite1 at "s places ) %ale4 ,9 ,ill9ois !y c be f\nd mo/ easily 9 ! ,w>saw ,=mation 9 ! area ( ,nauvoo1 ,hamilton1 & ,w>saw1 b !y also occur 9 o!r areas & o!r =mations4 ,,animal ,,fossils 7#cd7 ,prehi/oric animals liv$ 9 wat]1 on l&1 & 9 ! air1 & left bo? direct & indirect evid5ce ( _! exi/5ce1 evid5ce we n[ call fossils4 ,millions ( anci5t animals di$ )\t leav+ a trace1 b "s1 especially ^? t _h h>d p>ts su* z %ells1 bones1 or tee?1 may be f\nd pres]v$ 9 rocks mu* z !y 7 :5 buri$ b5ea? s$im5t on ! floor ( an anci5t sea4 ,sometimes only impr9ts ( ! outside or fill+s ( ! inside ( ! %ells rema91 ! orig9al mat]ial hav+ be5 completely dissolv$4 ,footpr9ts ( l& or amphibi\s animals1 burr[s made by clams1 or holes made by worms also are fossils4 ,illu/ration3 uncaption$ ,! animals ^: rema9s are fossiliz$ liv$ & di$ :ile ! s$im5ts t conta9$ !m 7 be+ deposit$1 & !y provide clues to ! types ( life & climate !n exi/+4 ,fossils ( animals *>act]i/ic ( a c]ta9 "t are an index to ! age ( =mations :]e !y occur4 ,= example1 if a c]ta9 trilobite 7an anci5t relative ( ! crayfi% & lob/]7 is kn[n to h liv$ only dur+ a def9ite "t1 !n all rocks 9 :i* x is f\nd are ! same age4 ,fossils ( animals t liv$ 9 ! sea are expos$ 9 rocks 9 _m p>ts ( ,ill9ois1 especially 9 qu>ries1 riv] bluffs1 & road cuts4 ,! olde/ fossils f\nd 9 ,ill9ois are %ells ( m>9e animals--snails1 corals1 cr9oids1 bra*iopods1 trilobites1 pelecypods 7clams71 cephalopods1 bryozoa1 ar?ropods1 & o!rs4 ,! y\nge/ fossils are tee? & bones ( prehi/oric bison1 giant beav]s1 de]1 mammo?s & ma/odons ( ! 8,ice ,age10 & snails f\nd 9 glacial loess4 ,,plant ,,fossils 7#ce7 ,,plant ,,fossils are ! rema9s ( prehi/oric plants4 ,woody /ructures ( plants aid pres]vation j z h>d p>ts ( animals d4 ,leaves & plants )\t mu* woody mat]ial g5]ally 7 well pres]v$ only if !y 7 buri$ quickly 9 f9e1 s(t s$im5t4 ,! mo/ fam\s ,ill9ois plant fossils are ^? f ! ,mazon ,creek area 9 ,grundy & ,w ,c\nties ( nor!a/]n ,ill9ois4 ,! plant mat]ial act$ z a nucleus ar\nd :i* iron m9]als accumulat$ to =m concretions4 ,_m good fossils--( trunks1 bran*es1 leaves1 & se$s--are f\nd 9 coals & 9 %ale directly ov]ly+ coals4 ,desc5dants ( 8,coal ,measures0 plants1 su* z f]ns1 mosses1 & ru%es1 are /ill liv+ today1 b !y no long] ?rive z !y did 9 ! w>m1 moi/ climate ( ! ,p5nsylvanian =e/s4 ,"s plants ( ,p5nsylvanian age are petrifi$1 & occasionally su* trees or /umps are f\nd4 ,petrifi$ trees are f\nd also 9 ! upp] ,mesozoic deposits ( s\!rn ,ill9ois4 ,fossils ( 8,ice ,age0 plants closely relat$ to =ms liv+ at ! pres5t "t are occasionally f\nd 9 peat bogs or scatt]$ ?r\gh\t glacial deposits4 ,illu/ration3 uncaption$ ,,keys ,,= ,,id5tification ,,( ,,common ,,ill9ois ,,rocks ,,& ,,m9]als ,two keys1 "o = m9]als & "o = rocks1 briefly pres5t clues t may aid ! collector 9 id5tify+ rocks & m9]als f\nd 9 ,ill9ois4 ,9 outl9e =m1 ! keys are a guide to "s ( ! easily obs]vable prop]ties t v>i\s rocks & m9]als display4 ,! rocks & m9]als 9 ! s*ool set ( 8,typical ,rocks & ,m9]als ( ,ill9ois0 are includ$1 plus o!r relatively common ones y might f9d 9 ,ill9ois4 ,because ( ! great div]sity ( rocks & m9]als 9 ?is /ate1 ! keys are n conclusive4 ,x is !re=e sugge/$ y consult o!r m complete keys 7su* z t 9 ,dana's ,manual ( ,m9]alogy7 :5 id5tify+ rocks & m9]als t are ei!r f o!r /ates or are difficult to id5tify4 ,! m9]als 7p4 #cj-ce7 are arrang$ 9 two gr\ps3 #a7 ^? ) a metallic lu/]1 & #b7 ^? ) a nonmetallic lu/]4 ,ea* gr\p is arrang$ accord+ to increas+ h>dness4 ,o!r *>act]i/ics su* z color1 /reak1 cleavage1 fracture1 & composition are li/$4 ,! rocks 7p4 #cf-ci7 are arrang$ accord+ to _! reaction to dilute hydro*loric acid appli$ to a scrat*$ surface4 7,! acid reacts m readily to p[d]$ mat]ial produc$ by scrat*+ ! rock47 ,aft] ! reaction to acid has be5 det]m9$1 ! texture & compon5ts ( ! rock %\ld be not$4 ,because rocks grade into "o ano!r1 cle> di/9ctions are n always possible4 ,,m9]al ,,id5tification ,,key ,i4 ,,metallic ,,lu/]1 ,,/reak ,,color$ ,c--color ,h--h>dness ,rem>ks ,"n & ,s--/reak ,cl--cleavage composition ,f--fracture ,a4 ,h>dness n m ?an #b4e ,c--lead gray ,h--#b4e ,v heavy2 occurs z ,gal5a 7#ca7 ,s--black ,cl--cubic2 cry/als1 gra9s1 or ,pb,s p]fect 9 #c masses2 easily directions id5tifi$ by color & ,f--subcon*oidal cleavage or ev5 ,c--copp] r$ ,h--#b4e ,v heavy2 apt to h ,native copp] ,s--metallic1 ,cl--none gre5 coat+2 di/ort$ ,cu %9y ,f--jagg$ or wirelike =ms2 malleable ,b4 ,h>dness great] ?an #b4e b n great] ?an #f4e ,c--yell[-br[n ,h--#e4e 7may be z ,9 e>?y masses2 ,limonite 7#bi7 to black l[ z #a7 color+ mat]ial 9 ,fe,o7,,oh7,h,o ,s--yell[-br[n ,cl--none _m s&/ones1 ,f--unev5 conglom]ates1 & soils2 (t5 mix$ ) & difficult to di/+ui% f goe?ite & o!r iron m9]als ,c--brassy yell[ ,h--#f ,z compact masses1 ,pyrite 7#bh7 ,s--gre5i% black ,cl--poor gra9s1 cubes1 & 9 #h- ,fe,s ,f--con*oidal to & #ab-sid$ cry/als2 unev5 commonly associat$ ) coal1 & ) lead-z9c ores ( nor?we/]n ,ill9ois ,c--pale brassy ,h--#f ,z fibr\s1 radiat+1 ,m>casite yell[ to ,cl--poor tabul>1 & cocks-comb ,fe,s 7#bh7 silv] :ite ,f--unev5 cry/als or compact ,s--gre5i% gray masses2 usually light] color$ ?an pyrite1 b difficult to di/+ui% f pyrite2 associat$ ) coal1 & ) lead-z9c ores ( nor?we/]n ,ill9ois ,,ii4 ,,nonmetallic ,,lu/]1 ,,/reak ,,:ite ,a4 ,h>dness n great] ?an #b 7c be scrat*$ by f+]nail7 ,c--usually :ite ,h--#b ,commonly f\nd 9 ,gypsum 7#bf7 b may be ,cl--p]fect 9 ,ill9ois z tw9n$ or ,ca,s,o#b;,h,o almo/ any color "o direction1 ne$le-%ap$ cry/als less p]fect 9 9 wea!r$ %ales two o!rs conta9+ pyrite & calcium c>bonate ,c--:ite or a ,h--#b ,z ne$le-%ap$ ,melant]ite %ade ( gre5 cry/als or p[d]y ,fe,s,o#g;,h,o coat+ on pyrite or m>casite2 has an a/r+5t ta/e ,b4 ,h>dness great] ?an #b b n great] ?an #c 7,c be scrat*$ by a p5ny7 ,c--colorless1 ,h--#b-b4e ,9 scales or 8books02 9 ,muscovite silv] :ite1 ,cl--p]fect 9 splits into ?9 %eets2 7:ite mica7 gray1 br[n "o direction common 9 s&/ones1 7#bc7 %ales1 & 9 igne\s 7,,oh7,k,al & metamorphic rocks ,al,si,o ,c--br[n or black ,h--#b4e-c ,z scales or 8books02 ,biotite 7#bc7 ,cl--p]fect 9 splits into ?9 %eets2 7black mica7 "o direction common 9 igne\s & 7,,oh7,k7,mg1,fe7 metamorphic rocks b ,al,si,o n 9 s$im5t>y rocks su* z s&/one or %ale ,c--colorless1 ,h--#c ,common m9]al2 ,calcite 7#bd7 :ite1 gray1 ,cl--p]fect 9 eff]vesces vigor\sly ,ca,c,o & v>i\s ?ree 9 cold acid2 occurs 9 t9ts directions1 n _m cry/al =ms & at "r angles z fibr\s1 b&$1 & 7rhomboh$ral7 compact masses2 *ief m9]al 9 lime/ones ,c--:ite1 gray1 ,h--#c ,v heavy2 commonly 9 ,b>ite r$1 or almo/ ,cl--p]fect 9 tabul> cry/als unit$ ,ba,s,o any color "o direction1 9 div]g+ gr\ps1 z less p]fect 9 lam9at$ or granul> two o!r masses2 associat$ ) directions fluorite 9 s\!rn ,ill9ois ,c4 ,h>dness great] ?an #c b n great] ?an #e 7,_c be scrat*$ by p5ny2 c be scrat*$ by knife7 ,c--:ite1 gray1 ,h--#c4e ,relatively heavy2 ,)]ite light yell[ ,cl--9 "o eff]vesces 9 acid2 ,ba,c,o direction associat$ ) fluorite ,f--unev5 & b>ite 9 s\!rn ,ill9ois b is n abundant ,c--:ite1 p9k1 ,h--#c4e ,9 gra9s1 rhomboh$ral ,dolomite gray1 or light ,cl--p]fect 9 cry/als & cleavable ,ca,mg7,,co7 br[n ?ree or granul> masses2 directions1 n eff]vesces sl[ly 9 at "r angles cold acid :5 p[d]$1 7rhomboh$ral7 m vigor\sly 9 w>m acid2 pr9cipal m9]al 9 rock call$ dolomite ,c--colorless1 ,h--#c4e ,9 fibr\s or compact ,c]ussite :ite1 gray1 masses or may be 9 ,pb,c,o grayi% black or?orhombic cry/als z a coat+ on gal5a2 v heavy2 eff]vesces 9 acid2 =m$ by alt]ation ( gal5a ,c--br[n to gray ,h--#c4e ,9 fibr\s or botryoidal ,sid]ite ,s--usually :ite ,cl--9 ?ree masses or rhomboh$ral ,fe,c,o b may t5d directions n cry/als2 eff]vesces 9 t[>d br[n at "r angles hot acid :5 wea!r$ 7rhomboh$ral7 slightly curv$ surfaces ,c--yell[1 ,h--#c4e ,9 cry/als1 9 fibr\s ,sphal]ite yell[-br[n to ,cl--p>allel to or lay]$ masses2 ,zn,s 7#cj7 almo/ black dodecah$ral associat$ ) gal5a ,s--light yell[ faces2 9 six 9 nor?we/]n to br[n directions ,ill9ois1 ) fluorite & gal5a 9 s\!rn ,ill9ois ,c--colorless1 ,h--#d ,9 cubes & cleavable ,fluorite 7#be7 :ite1 yell[1 ,cl--p]fect1 masses2 _m colors2 7,fluorsp>7 purple1 gre51 p>allel to m9$ 9 ,h>d9 & ,pope ,ca,f blue octah$ral c\nties faces2 9 f\r directions ,c--:ite1 t9t$ ,h--#e ,z cry/all9e ,smi?sonite yell[1 blue1 incru/ations or 9 ,zn,c,o or gre5 e>?y or compact masses2 associat$ ) fluorite-sphal]ite ores 9 s\!rn ,ill9ois1 ) gal5a & sphal]ite 9 nor?we/]n ,ill9ois ,d4 ,h>dness great] ?an #e b n great] ?an #g ,c--:ite1 gre51 ,h--#e-f ,9 long1 sl5d] #f-sid$ ,amphibole ,gr\p br[n1 black ,cl--9 two cry/als2 cleavage angle 7,mg1,fe1,ca7 directions important 9 7,si,o77,,oh7 int]sect+ at diff]5tiat+ f 7may also ab\t #fj & pyrox5es2 common 9 conta9 ,na or #abj metamorphic & "s ,al7 igne\s rocks ,c--gray1 d>k ,h--#e-f ,cry/als %ort1 /\t1 ,pyrox5e ,gr\p gre51 black1 ,cl--9 two & #h-sid$2 cleavage 7,mg1,ca1,fe7 d>k br[n1 directions angle important 9 7,si,o7 bronze int]sect+ at diff]5tiat+ f ab\t #ij amphiboles2 common 9 igne\s & "s metamorphic rocks ,c--:ite1 gray1 ,h--#f ,z cry/als1 cleavable ,feldsp> ,gr\p p9k1 light ,cl--9 two masses & gra9s2 7#bb7 blue1 gre5 directions common 9 igne\s & ,k1 ,na1 ,ca1 ,ba ne>ly at "r metamorphic rocks1 also 7,al1 ,si7,o angles 9 /ream gravel & s&2 _m v>ieties ,c--:ite :5 ,h--#g ,f9ely cry/all9e ,*alc$ony pure2 may be ,cl--none v>iety ( qu>tz2 ,si,o color$ by ,f--con*oidal botryoidal or impurities concretion>y masses2 l9+ 9 geodes ,c--colorless1 ,h--#g ,mo/ abundant m9]al2 ,qu>tz 7#ba7 :ite1 or ,f--con*oidal occurs 9 #f-sid$ ,si,o almo/ any color cry/als capp$ by pyramids1 9 gra9s or masses2 pr9cipal m9]al 9 s&/one1 also abundant 9 igne\s & metamorphic rocks2 is a v>iety ( silica ,c--r$ ,h--#g ,a v>iety ( qu>tz ,jasp] ,f--con*oidal usually color$ r$ by ,si,o hematite inclusions2 common 9 glacial & riv] s& & gravel f\nd along ,lake ,mi*igan %ores & 9 ! ,mississippi ,riv] ,c--_m2 ,h--#g ,cl\dy b&$ v>iety ( ,agate arrang$ 9 ,f--con*oidal silica2 widely us$ z ,si,o b&s semi-preci\s /ones4 ,onyx & silicifi$ wood are =ms ( agate2 f\nd 9 glacial gravels & upp] ,mesozoic s$im5ts 9 s\!rn ,ill9ois ,e4 ,h>dness great] ?an #g 7_c be scrat*$ by qu>tz7 ,c--r$1 br[n1 ,h--#g4e ,irregul> gra9s or ,g>net ,gr\p yell[1 gre51 ,cl--poor masses2 sometimes z 7,ca1,mn1,fe1,mg7 black1 :ite ,f--ev5 #ab-1 #bd-1 & #cf-sid$ 7,al1,cr77,si,o7 cry/als2 abundant 9 glacial s&s & ,lake ,mi*igan bea* s&s2 common 9 metamorphic rocks ,,rock ,,id5tification ,,key ,,sample ,scrat* ) a knife & apply dilute acid 7,h,cl7 ,if rock does n scrat*1 g directly to ,i1 ,,ii1 or ,,iii ,no eff]vesc5ce or v slight eff]vesc5ce ,i ,co>se-gra9$ 7p4 #cg7 ,,ii ,f9e-gra9$ 7p4 #ch7 ,,iii ,organic 7p4 #ci7 ,slight eff]vesc5ce gray1 light gray1 :ite1 or br[n3 ,dolomite ,vigor\s eff]vesc5ce ,compos$ ( pebbles t eff]vesce ,r\nd$ pebbles3 ,lime/one conglom]ate ,angul> pebbles3 ,lime/one breccia ,compos$ ( cry/als ( calcite1 fossil %ells1 or oolites3 ,lime/one ,compos$ ( b&$ lay]s ( cry/all9e calcite2 commonly f\nd 9 caves1 =m+ /alactites & /alagmites3 ,trav]t9e ,l>ge am\nt ( insoluble residue left on acid-treat$ surface ,individual gra9s se5 ) unaid$ eye3 ,calc>e\s s&/one ,individual gra9s n se5 ) unaid$ eye3 ,calc>e\s %ale ,compos$ ( por\s or cellul> mass ( calcite2 commonly f\nd ne> spr+s & wat]falls3 ,tufa ,i ,,co>se-,,gra9$ ,,rocks ,a4 ,rock consi/s ( int]lock+ gra9s or cry/als1 easily se52 too h>d to scrat* ) a knife #a4 ,cry/als align$ 9 "o direction a7 ,cry/als 9 p>allel b&s ) lay]s ( qu>tz & feldsp> sep>at$ by mica & o!r m9]als ,gneiss 7#f7 b7 ,cry/als 9 ?9 p>allel b&s2 t5ds to split into ?9 %eets p>allel to b&+2 "s v>ieties may be scrat*$ ) a knife ,s*i/ 7#f7 #b4 ,cry/als n align$ 9 any p>ticul> direction a7 ,light gray1 p9k1 r$1 or tan ) only a few d>k m9]als2 feldsp> & qu>tz pr9cipal m9]als ,granite 7#a7 b7 ,d>k to m$ium gray2 compos$ ( feldsp> & d>k m9]als ) little qu>tz ,gabbro 7#b7 c7 ,d>k gre5 to black2 ess5tially d>k m9]als1 may h "s feldsp>2 qu>tz g5]ally lack+ ,p]idotite 7#e7 d7 ,light color2 simil> to granite 9 texture b lacks qu>tz2 compos$ ( feldsp> & "s d>k m9]als ,sy5ite e7 ,l>ge1 easily se5 cry/als set 9 a f9e- to extremely f9e-gra9$ backgr\nd2 any color ,porphyry 7#c7 f7 ,ess5tially qu>tz2 gra9s may be id5tifiable2 specim5s break ?r\gh r ?an ar\nd gra9s ,qu>tzite 7#i7 ,b4 ,rock compos$ ( individual rock p>ticles or fragm5ts1 non-int]lock+ cry/als1 cem5t$ or n cem5t$ toge!r2 may or may n be scrat*$ ) a knife #a4 ,p>ticles or fragm5ts n uni=m 9 size2 a mixture ( pebbles1 s&1 & small] mat]ials a7 ,solid rock consi/+ ( p>ticles or fragm5ts g5]ally r\nd$ & cem5t$ toge!r ,conglom]ate 7#g7 b7 ,solid rock consi/+ ( p>ticles or fragm5ts1 g5]ally angul> & cem5t$ toge!r ,breccia c7 ,fragm5ts rang+ 9 size f clay to l>ge b\ld]s2 may be compact$1 b n cem5t$2 mu* clay g5]ally pres5t2 may eff]vesce ,glacial till d7 ,loose p>ticles ( _m sizes1 n cem5t$ toge!r2 "s p>ticles may eff]vesce ,gravel #b4 ,rock p>ticles or fragm5ts1 ab\t ! size ( gra9s ( sug> 7#b to 4#je mm7 a7 ,loose p>ticles consi/+ l>gely ( qu>tz ,s& b7 ,solid rock consi/+ l>gely ( qu>tz2 c be sep>at$ easily into individual p>ticles2 granul>2 breaks ar\nd r ?an ?r\gh gra9s ,s&/one 7#h7 ,,ii ,,f9e-,,gra9$ ,,rocks ,a4 ,_c be scrat*$ easily ) a knife2 cry/als or p>ticles n easily se5 ) ! unaid$ eye2 v h>d1 difficult to break2 may conta9 a few cry/als or p>ticles l>ge en\gh to see2 granul> #a7 ,d5se2 brittle2 spl9t]y or con*oidal fracture2 %>p edges & corn]s :5 brok52 (t5 associat$ ) lime/one2 usually :ite or gray2 v d5se1 dull v>ieties call$ fl9t ,*]t 7#bg7 #b7 ,light gray1 p9k1 r$1 or tan v>ieties common2 b\ld]s or fragm5ts 9 ! glacial drift ,felsite #c7 ,d>k gray1 gre5i%1 black1 or m>oon v>ieties common2 may h small m9]al-fill$ cavities2 occurs z b\ld]s or fragm5ts 9 ! glacial drift ,basalt 7#d7 #d7 ,ess5tially qu>tz2 gra9s may be id5tifiable2 specim5s break ?r\gh r ?an ar\nd gra9s ,qu>tzite 7#i7 ,b4 ,may or may n be scrat*$ ) a knife2 fairly uni=mly f9e gra9$ #a7 ,s(t2 feels slipp]y or soapy :5 wet2 may dis9tegrate 9 wat]2 gives (f an e>?y odor :5 brea!d ^u ,clay #b7 ,loose2 gritty2 p>ticles small] ?an table salt ,silt #c7 ,solid rock2 (t5 9 ?9 b$s or %eets2 sep>ates into silt2 mica flakes may be pres5t2 may conta9 fossils2 may eff]vesce slightly ,silt/one #d7 ,solid rock2 breaks into ?9 platy %eets2 may feel slipp]y :5 wet2 black to gray2 may conta9 fossils2 %[s ?9 lam9ations2 may eff]vesce ,%ale 7#aj7 #e7 ,solid rock3 does n break into ?9 platy fragm5ts2 may eff]vesce slightly ,mud/one #f7 ,solid rock2 usually gray or black2 splits into platy %eets or slabs2 h>d] ?an %ale ,slate #g7 ,p[d]y2 :ite or light br[n2 commonly associat$ ) *]t & qu>tz f :i* x =ms ,tripoli 7#ai7 ,,iii ,,organic ,,rocks 7,,d>k ,,color$7 ,a4 ,s(t2 spongy :5 wet2 v lightweight :5 dry2 =ms 9 swampy places #a7 ,f9e mass ) co>se plant fragm5ts2 d>k gray to black ,peat 7#ac7 #b7 ,plant fragm5ts small & n easily recogniz$2 f9e-gra9$2 black to d>k gray2 e>?y ,muck ,b4 ,h>d b c be scrat*$ ) a knife #a7 ,black2 conta9s b&s ( %9y & dull mat]ial2 burns well ,coal 7#ad7 #b7 ,d>k gray to black2 does n conta9 %9y b&s2 splits into ?9 %eets2 burns poorly or n at all ,bitum9\s %ale ,,equipm5t ,,= ,,collect+ #a4 ,hamm] 7bricklay]'s7 ) "o *isel or pick head4 #b4 ,cold *isel ab\t #f in*es long ) an edge ab\t -in* wide4 #c4 ,dilute hydro*loric 7muriatic7 acid 7#aj p]c5t solution7 9 a dropp] bottle = te/+ ! pres5ce ( c>bonate m9]als4 ,m>k ! bottle ,,poison4 ,if acid is spill$ on sk9 or clo?+1 wipe imm$iately &1 if possible1 r9se ) wat]4 #d4 ,magnify+ glass or h& l5s--#aj p[] is probably mo/ useful4 #e4 ,h>dness te/]s--p5ny1 squ>e ( w9d[ glass1 pocket knife1 or nail4 #f4 ,/reak plate--piece ( unglaz$ :ite porcela9 7su* z ! back ( a tile7 = te/+ ! color ( ! /reak ( m9]als4 #g4 ,notebook & p5cil = keep+ records ( ! locality & b$ f :i* specim5s are collect$4 #h4 ,collect+ bag--a musette bag1 a knapsack1 or simil> bag ( /rong mat]ial4 #i4 ,heavy gloves & goggles to protect h&s & eyes4 #aj4 ,labels & wrapp+s4 ,field id5tification ( specim5s may be writt5 on adhesive tape & atta*$ to ! specim5 or on a slip ( pap] enclos$ 9 ! wrapp+4 ,newspap]1 br[n pap]1 or pap] bags c be us$ = wrapp+ specim5s4 ,label ! outside ( ! wrapp$ specim5 too4 ,take only ! be/ specim5s home ) y4 ,trim specim5s to h& size 7ab\t #b by #c in*es74 ,all specim5s %\ld be label$ ) ! foll[+ in=mation3 "n ( m9]al or rock type1 :]e f\nd1 collector's "n1 & date4 ,z y\r collection gr[s1 y may want to set up a sy/em ( catalog+4 ,li/ specim5s & assign a numb] to ea* "o4 ,place a small am\nt ( :ite enamel on a corn] ( ea* specim52 :5 ! enamel dries1 numb] ! sample ) ,india ink2 coat numb] ) lacqu]4 ,correspond+ numb]s %\ld be ent]$ on y\r li/ ( specim5s4 ,,educational ,,ext5sion ,,program ,?is book 0 prep>$ by ! ,educational ,ext5sion ,section ( ! ,ill9ois ,/ate ,geological ,survey1 pr9cipally ,betty ,jean ,hanagan1 ,i4 ,edg> ,odom1 & ,%irley ,j4 ,trueblood1 "u ! direction ( ,george ,m4 ,wilson4 ,!y 7 assi/$ by o!r memb]s ( ! ,survey /aff1 especially ,j4 ,e4 ,lam> & ,j4 ,c4 ,bradbury ( ! ,indu/rial ,m9]als ,section4 ,educational ,ext5sion also s]ves ! public by assembl+ & di/ribut+ rock & m9]al collections = ,ill9ois educational gr\ps1 giv+ lectures1 prep>+ exhibits1 answ]+ qu]ies ab\t id5tification ( rocks & m9]als1 report+ ,survey news1 & conduct+ e>? sci5ce field trips4 ,dur+ ea* ye> six field trips are conduct$ 9 widely sep>at$ p>ts ( ! /ate = tea*]s1 /ud5ts1 & laym54 ,! g5]al program is especially design$ to assi/ 9 tea*+ ! e>? sci5ces & to help make ,ill9ois citiz5s aw>e ( ! /ate's great m9]al weal?4 ,ill9ois ,/ate ,geological ,survey ,urbana1 ,ill9ois ,illu/ration3 ,,ill9ois ,l& ( ,l9coln ,transcrib]'s ,notes --,sil5tly correct$ a few typos4 --,reta9$ publication in=mation f ! pr9t$ edition3 ?is e,book is public-doma9 9 ! c\ntry ( publication4 --,9 ! text v]sions only1 text 9 italics is delimit$ by und]scores4