Sheeprock Mtns Pages from USGS PP-111

8/14/2019 Sheeprock Mtns Pages from USGS PP-111

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?IOU NTAINS. 423cent lend, the higher grade. cu rrying 5 to 6 oxidntion produetso( thesesulphidt'S ingunrruesOU' lces of silver. A little gold has 1160 becu of tI I ' t I . ' "o ~ e, C.l cit e, nnd minor quartz . Th r-irreported. 1'ho .ni.ne hilS been worked in ter- USllnl silver cont ent averuges 3 to 5 ounces, but.lIlitt-ently und has shipped only aoout 15 enr- i l l s O ~ l e deposits rises to 10 OU IICt'S pc.r ton. .londs oCore in more th"l1 20 years. Ko zine The ~ ' z e 5 und shapes of tho ore bodies vury IIChRS been found. eOl'd ll;g to co nditions; some stmag fiSSlll'l'SAl'broa.lh minc.-The Arbl'Outh shoft is about contlllll contllluoU5 veins, ulllI somo pel'm eab lonu eighth of a mile nOI't.h of the YelJowstone, beds of PUl'O limestono :11'0 rnlh O' cx toIl.,;j,'e lyi.n 11 low spur w l ~ l p l t ~ n t e a tho south fork i'(,placcd; bu t nl'gillaccous unci dolomitic beds(rolll the uorth l ork of 1: cUowstolJe C,myon. hl1ve yielded only small bodies of high-gl'lldeTbo millennl on tho dnmp shows the mmerl1li- 1Ore ilnd IL fm," moro ,,,,to'L,i,,,; bodies of milling,ution to be of the sllme type us that of th e 01'1) .Yelluwstone mine. 'fhe OJ'e found during I 'l'h o 01'0 bodies of the Cllllyon Rnllrto nro noassessment work is reporterl to be of two oxc.cpt.ion to t.his rule. T h ~ o lllincd\","o I'egrodes, t.he highe l' currying 76 pel' cent lend "lured dolomit.ie limesl.oao lwds .I ULlO' their

!l ounces of silver and the lower 10 to 11 iutel':;ect.ions with ll..I'!'OW nSS\ll'es IInlllll: smullper cent lend olld 1 ounc,e of silver. Only u or of low gn"l". Tho highor-b'Tude 01'0 bodil>;;.mnll qunnti ty of ore h ilS been found tI,us fn r. mny be mined nt il O gl'cnt expense, bu t thoWood C'a.nyon yroul'. - Tho '''ood Conyon cost oC prospecting fllr new bodits "ft cr oldgroup "f claims is on the nort.h sido of Wood ones huvo become exhllllstcd is lil,ely to cqunlCllll}'on and includes the uppermo s t beds of the or exceed the ne t recoipts from me s"les.limestone formotion. The mineralized out- Smull coppl'r prospects found nenl' the lenderop is It brown, rust-stnined dolomitic bed , anti zille mines in sonIC (If (,],0 di st.ricts Illlnwclc.ont!lining n large nmoll il t of ferruginous dolo- fire q l l l ~ l ' t z VOilL'J ('ontlli.lling ehnlcopyrite andmito "pn.r, white WhOI'D fresh lind brown where . pyrito or Uwir oxid".tio)l prod:wts IIIHI lire",enthored, through which nrc scuttercrl groins eonfined to the siliceolls roeks- -'lunrtzite,(If galenu und yoIlo,,;sh-brown zinc blende. schist, 01' grnnit e. The copper prospcd8 ofThe st.oined mck is closely ussociatcd with two tho Callyon Runge may , f"om th e 1l101lgc.rfi,mres , oue t.rending north !tnrl th e other S. know ledge Iwuiluble, be cl"ssed with t.his type.55' E., bolh of whose outcrops nre marked by A Cew veins iutel'l11eliiuto in eompositioll be,h aJlo,,' gulches. tween tbese li nd the leatl and zinc dcpcsits hllvo

COPPER PROSPECTS. been found, 8ugg('Sti llg that, t.he two t.yP(\S Wt)rOderived ft'om II common sour ce. NOllU of til ('Sccopper-bellring veins lIppcllr to have yieldedsteady shipmonts of ore.SHEEPROCK MOUNT.UNS.

By r.. F. LoUOHLIN .

,\. small coppcr prospect ill qU!lltzite onlow ridge just north of the mouth of FoolCl'eck conyon consis ts of minerlllizoo white,ei" quartz with numerous fmctures sttlinedby 61ms of green and blue copper curbouat.es,and eontniningsmall spots llnd potches of rlnrk-brown iron oxirlc evidently dcriverl t.hrough GENERAL FEATURES .oxidation of pyrite l1url chnleopyrite. Other The Slweprock ~ [ o u n t . l L i (lig. 40 ) formCOpper and lead prospects hu.e been reported a nArrow mngc "bout 20 n ~ i l loug 0 t h l i ~ along Dry Canyon, south of Oak Creek. trends northwest ncross louglt.ude 112 30IW. Illid lntit.ude 40 0 N. Th ey lie between the

COIIPAIUSOI< WITH ORES OF OTHER DISTRICTS. ISimpson Mountaills on tho west und tho WestTho len tl nnd le.td-zinc ores of tho Conyon ITintic Mountains on the Cllst, uno form 11.Range lire simi},,1' in minel'fllogy und mode of southwlll'rl continunt.ion of the Onnq ui Rllnge,

o e c u ~ ~ n c e t.o certuin ores in the Noit h Tintic, separated from it hy ulow pliSS wes t of F I 1 U S ~ S . Im tlC, Suntaquin, und Mount Nebo


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424 DUE DEPOSITS OF UTAFI.d t I nooonoeci bu t the west- r u d c s . merging wi t.hou t hrenks in to theun wcs S Opl'S are pro u. .J,A. I 0. '.'.tl' t C' nyolls cut both the vlnl slopes which fn ngo 1]10 nl l:ge.el'll nrc Ie s cepeI'. u . west lInfl cust, blls es of the l'tlnge well back to- : M lw ) ' of Ihe caJlyons COI.lI:lUl l ' lllllUng Wwllcd the middle, Irnving rut.her a n'"Tow : ,mel the bottoms of t,hoso In I h ~ llorthernsinuous c)'('St line, Th ose in and nenr tho grun- : of th e ronge ore covered w,lh n rather

ite stock on the west slope (pI. XII, B, 1'.101) , t r ~ e g r o w ~ in m"rked con trust tho slire di stinctly "h anging" in churacter. 'They nn d IIllu"ltll slopes IInel 'Tlilcys ~ n t o wmllintllin bro"d V-shllJled cr oss sectioJls "Jld they empty. Alth ough the m ountmDSnl'Ouniform gonlly gruded bottoms throughout . watored, e,Q,n tho lurgcr s l r c u ~ , s ChgUPmost of th eir COUffies , bu t nl'U )' their mouths I cry nea r thcll cunyon mouths. These slr

LEGE:NDS f : D ' M E N A ~ ' " AOCKS,EaAllvvium

C Q " b o n u p p e r MiMis$ ipp'an) quartz-ite w,th Int.ercala ted~ t o n e beds , 1$

':... ':: .i l l"' ''. .: . .... -Ytrttbrian quarhit,.e'm-.:::l,. tmr:::Jp're - Cumbrj"'I"I1'

q ~ r t l ::.erie::.'IGNC.OU:; ROCKS

Granojiorite PC! rphyryend n ~ o n r

I,'IOU,I); . f R C ( ' o n ~ c e ~ ( ' O I ~ map crthe S h c c p r c Y.OUD(lllns IUld pu t of 11m Wlost TlnUo lfOlnl:Un.i.

the hattom. " I.cepen a\;ruplly lind their creek irrignte a few runcb es nen!' t.be buse of heds follow n sharp ly g z l l g course bet.ween runge.low verticnl wnlls. The re IIro no indications GEOLOGY.of glaciation, ond, os the b,,"o of the runge i.;; The Shee.prock Mountains (see fig. 46 )well I1bo"e the highest level of Ln.ke Boone- sist mostlr of sedilllcnLIl.I'Y rocb. Tho mvillo, loworing of water l


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SHEEPROf!I{ MOUN'l'AJNS. 425the soutbern elld of th e rnn!,c, hI t.he West.Tint.ic dist.ri"t, un ul'ea of limest.one "f undetermined "ge prob'lbly irw lucics Combrian,) ! ~ , i p p nlld perlinps in tcl'llIcrli ntl\ ti tl'lIt.ll,'fbis limcst.l>ne is sepnmtcd fl'olll t.h" IH'C-Cnmbrian (1) 'lwutzitie forrnnli oll by an ovcl't.lnustinuit, All the format,ions dip p"eva ilinglyllnrt.h ens(,n-ard, lInd nil dip Itt 1,,1" a.ngles, ('xc"p l.those of the southe rn limestone "reIl , most of\\'hi"h d ip steeply.Igneous rocl.;:s ore repl'(lscnt cd by nprominentstork of granite or gl'nnodiol'ite in the norlh-eent r,,1 part of the TiLlll'e und by SOHI',II slllnll,tocks of granitic" monzoniti('., and rhyolitic.rod" 01. the southern curi. Dikes ond sills ofgruuite., gnlJ1itc or rhyolit e porphyry, find mon-7.onite or diorite porphyry arc Itbundant inI' lo,,('s lind lO"'e been noted in the vicinity ofall i n N " l i z orens.

COLUMBIA AN D ERICKSON DISTRICTS.Tho Columbiu dis trict and t,I;" eastern purt

of tho Erickson dis t,r id (the western part. is intho Simp"')i1 ~ [ 0 U l . I t.nins) lio in tbe slime mineralizer! I l r l'8 in tho llorl.h-cent.ral pRrt of th o rtlngc.The Colllnlhi" district lies ellSt and the Erieklon distriel west of tho diYido. 'fbe geologiclonn.tions iJiclude pre-Cllmhrinu (1) and CUIlI-hl'inn :;cdill1C'1l tl1.1'y rocks, th e lnl'gcst gl'tlllitestock of the rango, and dikes of rhyolite undmonzonile. porphyry.

GEOLOOY.SEDUlENT..utY RoaRS.

The sedimentnry rocks overlio tho intrue.i",granite, striking from northwest to west lindt1ippingnortbenst of nort.b. Ncar tho intrusivoCO:t!Jld t.his dip is I'll ther steep, avern.giJlg about15" N. or )fE., but i t nppcU.l'8 to flatten as,ilstnnre from the c{)ntl1ct increnses.The pre-Ca.mbrian (?) inclndes hcds of pure

nor! of durk cbloritic qUllrt7.ite, cbloritic sbllle,and poorly assorted conglomern tc. A sectionthrough t,he upper pnrts ()f H n r d - t o - n Canyon On the soutbwest nn d of Harker Canyon?n the northeast of tho divido shows in IIsceudlllg order, first n zone of prcvailill"I)' Ii"ht-1 J I:' . bco a ~ e d quurt.zite just "hove tbe intrusiveg"on'Le contact; second, " scries of chloriticconglomerllte., quurth, ond sholo; thi.rd, 0 zoneof pl'evnilingly lirrht-colored qunrtzite' undfa h " ,Eun ,n zone of green, purple, Dnd hlllck shole.. . .


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426 ORE DEPOSITS OF UTAH.IGNEOUS ROCKS,

The granite form. tim south and southwestprecipitous fronts of the rlillge and extendswell up the cnnynns to within a mile of thedivide. Its upper contllCt slopos eastward andprobably nort.hward, eventulllly d iSl\ppcaringbencllth the surfaco . The low flnt ridges att,]le south bllse of tllo mnge are a130 of disintegruted grnnite which pusses insensibly inlo~ h e ll11uvio.l slop


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S H E ~ l ' n O C K )lOUNTAINS. 427conccntnllor, equipped with roll., Iltlllf.ingtO!l The Will! rock, whether n.rkose or grunite, isscreon jig;;, nnd WIlliey tubles, Was bUIlt. altered to I I I l uggregute of qUllrtz und sericiteSome lead coneentrn t{1 WlIS sh ipped in 1908 nnd wblch in pl!lces is impregnated willI con~ 9 0 ( 1 , nnd s h i p m e n t . ~ of leuIl-zinc sulphides sidcrnble speculnrite. GIlIC'nn seems on thehn,"e hrell reported.' In 1!114 t.he lessees were whole to bo limited to the veins. The tot ...1shipping It fnir grude of crude ore. width of tho vcined and imprcgnutcd zone in

OIU: Dr.pOSlTS.OCCU1lRENCE. AND CHARACTER.

The OI'C deposits ,Ire veins in granite or inqUlll't7.itc, nono in linu">.stono h(l\"'ing h(wll re-portrd. They may be clnssiii,d os qUintzfeldsl",r veins carrying spc


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428 onr. n E O I T ~ OF t:T. \H.fe!'t. Nothing definite can he said regoruing to limonite, finel by the filling of fiuothe horizon(,,! extent of the Teins or of the c1eu\,flgo crotcks and smtlll frn ctnres in bproportion of rich gronnd in the whole vein. veins (Iud wfllls with mlll(lchi te and iron oxThe vein minerals vary in quantity, nnd all Small vu:"'S m ll-,l' be partly fiJjed with whitof thl' m are un t present in oll specimens. Tile pole-brown lm.olin, evidently introducedgenom! nrnlJl"ement l'ud"i!!" from specimens chanicolly by infiltrating "'ttters. Th e inc" , 'd' d 1 I IIon tho dumps, is for fluorite and the sulphides plotn"""s of OXI "tlOn on tIe s 10 uw doto sc"rc"ate near tho ma",ins of fissures aud I o gl'Ound ,,",,tCl' 8\'e not fttvorable to the oe1:7 0 for OUflrtz to jill the wntrnl portions, but tlU" , rcllCO of nny stl'ong zones of enrlcheel sulphit t r l ' l l ~ " e m c l l t evidently depends on the (Ic.grco and it is probnble thllt the value of tho Orto whieh the differont minerals have been nble It wholo will no t improve with dept.h. to "egregntc. In spedme",s showing the mar- copper content of the ore on tbe dumps dgins of veills tho gl'\lnite retnins it s nppoarance, no t avoroge much if any over 5 pel' centbut the original biotite is replaced by smoll nothing indicates It high tenor in silver.pYl'ite grains, and the plngioclnse by It soft The pcincipal workings in this type of vyellowish-green material (presumably 11 micro- arc t.l:oso of the C o p p ~ r Jack 'Mining Co., ",Iscopic aggregate of sericite and siliel1 possibly los o p ~ r a t e d the CoppOI' Jo.c.k and Flystllincd in places by green copper minerals); Dutchman shafts. According to C. C. Grigthe Illkalic feldspar und quartz have undergone president of the company, the Coppel' Jno Ilppreeiable chllnge. Tho vein contnet is shaft is 140 feet deep !lnd follows u 3-foot ,shurp but not stmight, suggesting that n par- which Itveruges 6 por cent coppel'. The Flytion of tho will has been replnced. The Dutchman claims have two inclined shafts,fluorite forms single crystals and coarse- of which is about 240 feet long with a slopgrained aggrega.tes of colorless to purple. about 40 and follows a 'loin considol'f(green where st!lined with malachite), either richer in coppor than the Copper Jack. pllro or mixed with the other minerals. The width is 3 to 15 feot. 'The Copper Jilek shpyrito IUId chalcopyrite also tend to form sepn- struck n strong flow of 'vater at o.bout 80 frnte aggregates, and sarno specimens 81'e com- and water was standing w i ~ h i n 20 feet ofposed almost wholly of chnlcopyritil and fluorite smfnce when seen by the writer. The win irregulllr mosses, but others nro composed surface in the Flying Dutchman shaft is scrueJ1y of fluorite nnd pyrite. Quartz forms 0. to stand about 100 feet down the inclmatrix for tho other primary vein minerals Four veins are said t.o ru n lengthwise (avnml olso forms small prisms of late primary or nge trend, N. 30 W.) throngh the propeseeondury origin clang minor fr8ctures. Study Their 8verago copper content is 3 to 5 of polished sllrfaces I1nd thin sections shows cent, but one lOO-foot portion of the Copth"t the pyrite and fluorite finished crystolliz- Jack vein carries 7 or 8 per cent and incluing about the same time and earlier than tho co,",siderablo high-grade materiol running 20other minernls. Some of the pyrite crystals 30 per cent. The silver ra.nges fro.:1l 1 twore distinct.ly eurlier than the fluorite. The ounces per toll.chalcopyrite 8.lId qU'lrtz erystllUized together, Tho ot.her properties in tho vicinity are thhut the quartz continued to crystnllize after of the White Rat (formerly the New Utt.he chalcopyrito hud all deposited. This orde.r, Milling Co. and th e Right Bower Miningpyrite, fluOl'ite, chalcopyrite, quartz shows the Their ore and gangue are of the same typeorder in which the minerals finished crYst


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SHEEPnOCI( ).fOUNTAINS. 429LEAD-znw VEINS.OCCURlu:XCg . \ ~ U CH;\RACrt:U.

The quart., voins with zinc and ICfld mineral.I primary sulphide, lend carbonate, and limonite,

buL nothing is known of their relative Mnolmt.s.The wnll rock inoludes a large Ilmount of thechloritic beds tho.t h.lve boell replaced Hndimpregnated to some extent by ore. The ol.erecently mined by lessees hus beon hauled bywngon to Duuhnl', n station on the Los AngeJes&, Salt. Lako Ruilrof1(I, nbOH! 12 miles to the east.

The New Sultanll Ore hody had not beenopened ut the time of the writelOs visit in 1012.It is rcport,,,I' to be n yein 4 feot thick inquartzite, nnd the ore is said to coutnin 60cents in gold and ;) ounces in silver to tho ton,48 pcr cent lend, nnd 28 per cent iron. Thezinc content is not known. Ono hlmdred tonsof ore nre said to have bc cn mined in 1914.

found on t.he upper slopes of tho range 011~ ~ h sides of the di"ide and h ~ v e been wOI:kedin Harkers, Albert EkI".

The nIue n olls district. lies on the enst sideof t.ho Shcoproek )'Iouutains, about 6 rutlessou ~ h c u s t of the Eliekson district lLnd closeto the sou th bOlmdury of Tooele County.I t is renched by .. 10-mile wogon road fromLofgreen, on tho Los Angeles & Salt LukeRnilroad. The road extends westward fromLofgreen aer(hOS a low PIISS in the WestTintie Runge, und turns s o u ~ h W t l f d ulong


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430 ORE DEPOSITS Q t' UTAH.Vernon or Fnust Creek to Green'. much,,,'horo it turns ,,estwnrd nguin I\ IOllg n. shnllowCllllyon t.hrough t.he. enst foothills of theSheep rock Mow l tnills.

( ) D 1 ) C T I O ~ By V. C. RruKES.The nIuc Bells ULqt.rict W l l ~ orgllllized onFehruary 12, IS06. It s known produdion hasbeen small.

OreY G\ T. (:-.hort

phosed shuly rock, gmuite, nnd gneiss inmlltrix of Shllly chnl'acter. Tho pobhles,c0,052 2,052 2l!JO.l . . . . . . . . . . . . . . . . . . . . .. .. . . . . . .. . . . . . . . 21 .41 8 354 203 2i1,975 1,(H9 1lOHi . . . . . . . . . . . _,_ . . , , . . . . . - . . , ' . . . . . - . . 12 .1 2 2 27 1 139 12, 'iH &84 ,1917 . . . . . . . . . . . . . . . . . . .. . . . . . . .. . . . . . . . . . . 12 .... .... ..... ... 297 2-15 9, 2;;8 i OG49 5.11 lOS I 4, !)45 I 3, 179 I 81, 557 12 , 731 16

GF.oLOGY.The only sedimentllry formntion notedwus t.he great 'sories of early Cllmbrian orprc-Cnmbriau qunrtzite, shnIe, ond couglomern te, which is SO prom inen tly exposed in thoErickson I1nd o,lumbin districts to the northwest. The stmtn r.t nnd nellr the cres t of therung", ,uoWld the MOl'g1l.ll workings, strikenorth ...es t 0 nd dip 40 NE . A mile or moreto the east, "round the BlM:k Hllwk workings,they strike nellrly ellst and dip north n.t n lowIlogle. Not euough work has hcon done todetermino the structure accurlltely, but the'stmltl "ppell!' to form 11 monocline, hroken

by mujol' a.nd minor fiLUlts.Tho qunrt7.ite members of t.he soril'S Ilrelight . to medium browu, medium grnincd,nnd ) l \ plnees cross-bedded. Tho shnlo isgreonish gruy wb ere fresh ,, 'id brown wherewonthered lind hilS " more or less metlllOorphosed nppcnrnnce, loen lly with tho chnr.ctel'Sof sla t{) or O\'cn phyllite. Tho conglomerl>teis typicnlly unn ssorted lind is composed ofsubnngullu' pobble'S of qUllrtzitc, met.ilmor-

monzonite porphyry, abou t 200 feot , ,exposed on II high short spur just nort.heof tho }iol"jllO sh.ft. I t lies betweensouthwcst wnll of quartzite .>lId n northewllll of shllle, relutions which .suggest thn\ms intruded nlong 1< fnul t.The prineipal structuml fO fCture, other ttho model" til degJ'cc of folding nlrollrly mtioned, is fllUlting. Ftlults of rnther smdisplilcemcnt und fissll\'es nre numerousthCl limited Ilretl oxamined, bu t not elloobservntions wero roo.de to determine directions of t.ho principl11 systems.strongest fnults and fissuros noted trN. 40 W. with dip 55 SW., N. 30 E. with70-80 SE., nnd N. 85 E. with dip .b50 S. One of t.ho N. 40 W. f!lults is IUlOponied by accessory. fissures, clm\"llcteriby breccintiou but little or no IlppUdisplncement. Those "ccessory fissures trN, 60-70 E ., north, N. 20 E., nnd eThey were noted ouly Ilt ono place,Blllck Hl1wk workings, wbero they Ilppeut.o radiate from 11 N. 40 W. fnult.


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SHEEPROC1( MOlTXl'AtNS. 431OltC DEPOSITS. :n t , ~ , a mntri" for the ore mineruls lind

IIINES, smull well-formed crys'tals linl" " 't ' 'AI . . . '0 CU.Vl ,l C'S . STho ouly orc (epo.'lts mport,'d in t1:e mile a m u t ~ J : ' lU leached plnees it ll; n white or lightl l s dL,trict fire those Oil th e R, R. P. p:op- hrowUlsh honcy-comhed material Th b ' ' t ,, b ' I d t . . e url {.

erty, wIlle me u cs wo groups of ,,orki.:Ig>', C U I ~ lU typical platy crystals, some hill! anthe Morgan and the Blnck Hawk, lOch I I I length, tbinly sC


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432 ORE V[;PO:;;JTS or UTAH .bedding planes ullowed tho solutions to pcrm ~ t l t e and replllce the rock more thoroughlythun elsewhere. All deposits so far di,;co\'ered"rc small, and furt.her pl"I)spec.ting is likely \()result in the discoverv of additiunal smullshoots mther t.hao of p ~ N i s t e o t ore bodies.

WEST TINTIC DISTRICT.Hy(i. F, 1.0lfGUJ,IN.

G";OORAPIlY.

Alt.hough tho WC$t Tintic dist.rict proh:lblyinelu


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433tho q u " r l ~ i l e series except on I ho soulh ,whe.re it I ist.rit't 10 t.),0 e"sl r b dI , I ' U ', l\W an SOl 'O cherlyis bordered by .1 IUVlllm, ts northel'll hound- Opt.i("11 on,\ ell '1111" I t I he '. il J I ' " <


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434 onE OF.POSITS OF UTAH.unblenched oolOlnitc. More intense motamorphism nCIHcr the i n t r u s i \ " ~ i g ~ c o l 1 ~ .cnn -tllets hos developed:t number or typ,col ~ I h e a t e minerllls, tho mo. . t conspicuolls of Wh1Ch nreglLrnet. Imd epidote; diopsidC;' t r e r ~ o l i ~ e , hornblende ILctinolite, pWogoplte, tltnnrte, und, . 'chlorite nrc prcsent 'ill fine to mIcroscop'c gl'llYto green nggl'ogntcs, some of which r ~ e l 1 1 ~ l e chert in nppenrnoee. These metnmorphlc mmemls tend to form nhundllntly ill errtll.in layersnnd to be bounded by Inyen! of grnnulnr colcit.,.The presence of cokite li S the nreyniling corbonotc in the thoroughly metamorphosed rockis in mllrkcd cnntmst to t.he prevlliling dolomitie churllelcr of the unrnetomorphosed rockA bed of shllly limestone. which rno.rks IIpproximutely the'upper limit of t . h ~ ore hori:-onin thu Scotill. mine, dc 'crvllS speclllI mentIon.At onl' plnce nlong its outcrop, sonthc8st of theW"llwr shuft, it forms the hllnging Willi of anold open-cut. stope wbich yielded bononzll orein the enrly


13/22

S.FlEF.PROCI( ::\(OCNTAJNS. 435qu art.?' JQoll1.onit" !;\'Oups. Th o 'must n]kalie I nd ends northwfistwnrd '11"1 t. ' ' . ~ . . ' ,,-, n. SI m If \ quar z-(salic) vnrlety noterl b n mu" .. ! ; T t t ~ l t o , '\llG Ite SO ri es . Anothor slllall stock just \Vest oftbe OlO$t ferromugnos lllll (muf JC.) vur\Ctv IS a [Illi; one ll.l'o cu the th t 'r l t. ... " ' ' ' ' ' . er, rus '. lese " ~ o dioriticphns: of m O l l ~ O n l t e . . s t o c k ~ consist 'of gr"J.nodiorito porphyry, with

Tbe rntru.lve bodws nrc fOI t.he most purt promment phenocrysts of feldspnr bu t nODlI of.mill, IIlId most of t.hem lire gl'Oupcd In Illl eRst- quartz in fLO nplitic groundmllss. A sllllillnortheast zone nellr the northorn boundary of IImount of u.lt.rrcd biotit.o "1ll1 :3 or 4 pcr CO\lt oftbclimlR tone nrctl.. A ~ m n l l eO.mphe-oted stoek, oxidized pyritc gmills am ",ho pmsClt. Inmuch obseured by d6bflS eovo\'lng, 15 pre.sent III thill section most of the pl'>gioclllsc is too mnchtbe sou thwest pnrt of the nrCII , and dIkes of sericitized to be ident.ified, but. " f"" ~ r . l . i n s granite pO'1lhyry and monzonite porphyry .r e indicate c.ucic '\Ildcsino. Dioti te is .Jtcred"ery 6b,oo (lnnt, most of t.ho se noted trending a to "WO\;te. The grOlmd111 I\.''l !:onsist", of qn'lI.t.zlittle eust of r t ~ or .\ littlo north of east. No i nud }oldspar, mos t.ly in gr,\phi,} intcrgrowt.h.dist.inct .ge n,lntlOns h"vo belm found. The foldspar is much knolinized bu t nppea!'s toGra1!oa'ioritc grou.p. - A s tock of roughly tri- include both ll.lk"lic und plagiocill.'le y.\riet.iesAngular outline is expo"ed "!ong. t.J1O curving the lntter less erucic t.h'\l\ the p l a g i o c l a s ~

ridge nOI'thwest of tho Scotill. lOme. I t con- pheno..,rysts. The pyrito is nssocintcd with,ist.s mostly of light-gruy coarse-grained, COll- serieite, secondary qunrtz, nnd chlorito, nndsidernbly disin tegrat ed rock, wit.h millor v n r i , , ~ is clenl'ly nn ruterntion produet.. TIus roek diftil'S of nplite und granite porphyry nlong tho fen> from t.hat first described mllinlv in the "bborder. Contact metumorphism along i ts bor- senco of qunrt7. phenoc .ysts, t.hong1; it eont4\insd"r is expressed by induru tion of shale beds in u largo "mount of qUl\rt .z in the groundmn,;s.tbe quurtzite nnd by fl light ultemtinn ill the lId- Anot.her small stoek (not f l c c u r n t ~ l y outjn cont.part of. tho limestono. The minernl com- lined in fig. 47) onle.rops t.o th e southonst justpos;lion nnd texture of the conrBe-grnined roek IY('l;t. of the overthrust contnct. This rock isis e&lentiolly similar to t.hat of the larger light pink IlJld composed of plngiocln.se, biotite,gr.nodiori!e in the Cdumbin-Erickson distric t and a f"w hornbk-ndo 'crystals with s(:l\t.teredto t.be llolthwest nnd on Des er t Mountnin to fmo grnins of n:n,,"IIet.itc Imd tit",]itc in .. n "xthe sOllthwt'St.. tremely fine grnined grollndm"",. In thin see-Tho border porphyry phase is of interest for t.ion thc feld spar phenocrysts prove t.o beromparison with the vurintions i:J the other mo stly plngiodllSc wit.h " few of micropl'rt.hitestocks. It consists of n ,'cry fine grained (Or"Ab,,) . Tho plngioclase includ.,s t.wogrolCldmass with prominent rounded grains of vnricties; L


14/22

4:3(; ORE OEI'OSln OF \;T.\H.inclusions of plugioel,c",', The remli lltdcr isplll.giocluse---{)ligocl",e-unal'sinc (An,,) mLhmore sodic outer zom". The muscovite (.endsLo form poikilitie eI"},stlLl. inclosing small we.ll{;rystJ.lllizcu grnins of quartz, Imd appears to'havo been 011 th" wholo the hl.tst importnntmincml t.o eryst"'llli7.c. Tho minor constituents110tcd nrc hiotit-n, separfLte or intergtm"ll wit,hr n u ~ c o v i t c ! magnet.itc, unu zin;.on.The compooitioJI of tills I'o< ,k is very similort{) LhlLt of th" groundm,,,,s of the rocks previously descrihed (p. 13.'i). Those rOcks cont a i n l ~ d 110 primn.ry m l l s c o ~ j t e , but the prt>Scllce{)f musem'itc ill this rock mny well bc ILLtributedto f\. gront.cr conccntl'ut.ioll or W:l.tO" tLIld fluorinoin "s",lic port.ion of lingmu .,nd docs not ne("'Ss"rily imliciltc the inLrusion of a distinct.magma: In other words, the mu scovite gl'lwtc.is rE'gurdt;d u.s rL saJic difi'crcntin.te from thegrR.llodioritic mn.gm:l.

The lllrge Urell oi granite porphylJ' and rhyolite porphyry northellst of the limestone lU'eILhus tho SIlIlle general composition as t,ho grunodiorit.ic rocks, bu t purt of it. difJOl" in po,sessillgtextures ch"rncteristic of effl"ivo rocks, Inspite of these text,ures all the contllC(s with theqUlI.l't.y.itc s e r i e ~ on the west arc lIcit.rly vertiCil.!I1.lld int.rusive. To t,he eust, however, tho rocks.me in part cleurly ex(.rusiyc, lind it. is conCludedthl1t the mltin vent, t.!\I'ough which thc h,vtlSof the rt'gion wom erupted is in the W(,sternpart of tlus "'cn.The greuter port of tite rock in tltis vent'mrics in textmc from very fine gI'niIIcd porp h ) ~ ' Y to rhyolite> porphyry, u!though sevoruleI'Uptions Itro represented. Much of it is lightgnty, dense porphyrit.ic, nnd contains ..bundl1ntphenocrysl.'3 of qunrtz und feldspar, with alittlCl biowte und magnetite. In thin sectionthe qu"rtz pheoocrY3ts show resorption andIDI1ny of t.hem arc cracked or even" faulted"the groundmuss filling the frnctures. Thefeldspur forms. roughly rectungulnl' grains,somo o.f the.m wlt,h resorbed rims. Plugioc.luse("ndesmo) IS somcwhllt more abundant thllnIllkulic fl'ldspur, n few grains of which hnvo I ipoorly defincd st.rud-me sug"estin" niiorocline.B ' . e bIOt.ltC und minor acc


15/22

SR EI.;}'H.OCK MOUNTATNS. 437Sps)'. The micro$copir. fJl1nrt:t. n : m ~ u n ts toelld\' 10 pOl' C('nL of tbe 1'o('k BlOt.,tD form;;n , . htypirit} grniIls, ~ o r o e . \ \"It . r p s o r b l ~ d . margins.Auuite f O l 1 n ~ pflsnw t.le g-I':l ms uVt\l'ngmg about n ~ i l l i U l p t e 1 ' in le.ng-th nnd ,hawing' 'nll 'tges01 I.he t.runsit.ion from fl'l',h nugite ir,to r.ompnctgreen bomblr.ndc wit.h typierd cll';1v"go (Uldpleochroism . Some the nugit.e, (or homb J ~ n d ( ' : gl'ums arc mtergrown wIth \noLlte.Minor ntcl>SSo1'ies include rn thpr uhundnn Ltitan it.e find tnngnetite in irl'el!ullll" to hypnutonwrphic. grll ins, Ilpat.it" in typiml well-formedprisms, nnd I'llI'd)"" zircon.

Besides the t.ypicalroek "nriations of cliorit-iechal'l1Ct.cr nrc prpscnt in the mon7.0nite stock.Somenre feldspathic.; ut.iwrs l,avD I pl'opondernnco of black minerals. In the feldspathicvoriety the plngioclllse hilS ahout tho snrnecomposition as in th e typicnl monzonite, bu t"Iblic feldspili' and qunrtz are very sCl1rce.Biotite is I.he princoipnl necessary nnd is ftccompnnied by " littlL' urlllit.ic hOl'llblcnde (nfler ',mgilc!). The darker variety consists of %Onlllplagioclnse, averaging ncar An:,o in eOJnposition ,and primary hornblende uceompunied by 'alillie biotit.c. No uugite is present. Alkalicieldspar nnd qUl1l'tz form fino inte rstiLinl oggregHlcs among the predominnnL' m i n ~ r a 1 s . )[Agnetite, titanite, and upnl-it.e, t.be firsL two frequently of megascopic size, are eonspicuousminor cOllsLituents in both "ariel.ius.

AlI.erat';on.-A1tel'l1tion has nffected .11 t.heigneous rocks of Lhe disLrict to u greater or lessextent., bu t th e kind of IlltemLion is th e Sil-mo in.11 of them und is of th e propylitic type. Thecommon nltern.tion minernls lire sericite, chlorite, epidote, cnleite, qua.rtz, nnd pyrite, andthese r . r ~ accompanied in some of the rocksby uralit.ic hOl'llblonde, secondnry titnnite, nndmugnetite. The relat.ions of these rninerrus toone Illlother sho,,' that they wero formed nt thesame time, nnd t.hey are at.tribnted to t.ho il-dionof heateu waters' thnt pel1nellted tho rocksd\ll'lng ore deposition. Knolin and limonitea.re the principlll minemls formed since thatlime by surface wet\thering.

Patagf1l.es;s.-The different intrusive rocksof the district Itre closely relnt"d. In some themore calcic plagioel.se an d t.ho black silicates:rCC?ocenLr.ted in relatively large proportions ;ud In one, the muscovite granite, the quartz

nnd nlknlie feldspnrs nrc cspecinllvconcentrutcdThe plngioclose is contained mni'nly in the pho:noer),s!s or earlwr-formed minel'"ls und thenlkillic feldsp.rs muinly in t.he grnundfTIliss orlatN-formed minNnl. of tho intcl'mcdinte(grnnodiOl'itic) rocks of tho district. Sufi'leienttime to allow certnin degrP


16/22

ORE D I ~ P , ) S I T S OF UTAH.o \ ' t - : I t T n R U " ' . 1rit.hin tho limC'.... tono urea. n low ridge

Tho sl.ruelU"o of t.ho liDlest.one is thus un- o( Lho "'''f Eoglo No.3 opon cu t ;s cappsymmetr ical wilh r.'spct.L1.0 t.he quart.zitoserics, quarLzit.e but. consist.s ot.herwise of steeplllnd other diseordum'c" in posit.ion oxist between ping limestono whose ~ x p o s u r e s surrounthe t.wo l'Ocks olong the c.ontac.t. The disap- quort.zite. Tho quart.zito is not. int.orcn.lnpellrunce o( the thin quort.zite bed in t.ho enst- the limestono and is regorded flS a remnaern limcst.onn orM bonenth the great quortzite. tho groot qUllrtzito sories wrueh onco oy~ c r i n g hils ! ~ l r o l l d y he(ln ml:'ntioncd. This st.rur- tho Ernest-onn.ture cithor implies the very !'lipid pinching out. The cvidoneo, oll.hough obscured "longof som" hundreds o( feet of limestone "nd thei r of t.he cont.llet by dGbris, nil points t.o discoequally 8uddr.n reoppearnnee just. to tho nort.h, I'cllttions bet,wcon tho limestone and quor01 ' is due to Iln ovurt.!lfusL The at.titudo of tho wruch, coupled with tho stroligrn.pruc ovibeds is nppllrcntJy conformnhlo nt t.he Scot.ia all'Otldy given, indieatcs nn o\'ort.hrust famine, hu t n shnk, mernbor, which immediately undulnt ing chol'act.m. Th e limestono areo\'orlies the lime'stono, is hcvoled off hoth t.o the complotdy cov(lJ'eu by t.he qunrt.!.ite neost ond wcst. At. t.ho snddle hotweoll t.he I .imo, tho fnult. eontnet orching oyer iLSeot.io Ilnel O,ient.mines osmoll muss 01 'luartz- rogord t.ho contact. a . ~ an u n c o n f o r m i t ~ ' w. ite rest, 011 limestono, the contact dipping necassonl}' Imply un Immenso trucknc>'S onort.heust III. II 10\\' lingle. .Just. south o( t.ltis Camhrion limestone in tho West. Tint.ic d iPoint . on t.ho l,iuh Iimestolle rid"'e tho lime- nnd nowhere else in the Great Easin rc 0 b Jst.one strat,1t st.rike a Iitt.lo eost of 1I0rt.h, bu t Furt.hermore, no frogment.s of t.he limeI,he limosl.ollC-'s tho Orient. and Virginia. Lode monts havo beon (OIUlll iu tho overlying qucloims wit.hout mgu.rd to t.ho strike and dip of it.e, whoreas t.hostruct.ural dr.tails of t.he cot.he limest{)no. At tho Virginia Lode prospect ara indicat.ivo of disturbance.tho linwstonc is separoted (rom u shule member Resnlts of 0 brief roeonnuisslmco in thoof tho qUllrt.zito by a nearly vort.ical cast-west Tintie Ranga o.long tho Tintic Rood londfault. From this point westwurd t.he cont,act port to tbe foregoing intorpretation. Alonis complicated by t\\'o smull st.ocks and a fow road the sedimentllry rocks consisL of quardil{(s of grollitic Ilnd monwnitic rock. with intercalated beds of shalo and lime

At. the northwost COI'nel' of tho limestone dipping west.ward I\t 0 low angle. Fossilaroo tho limestono strikes 25 W. Ilnd dips loct.ed from two Iimest.onc beds wl'ro dnon .rly vert.imlly, bu t t.ho quortzite cont.act mined by G. H. Gut.y, as follows:curves from east to west through an Ilnglo of ned southwest of Summer mnch: Sponge?, Zapliabout 1 .5 to 0 trend paralleling tho limestone sp . Bdlcropho" .p.bedding. Sout.hwI\rd along t.he west.contact. tbe Bed lO() yard. north of the )bmmoth re,ervoir:at t,itudo of t.he E m ( l . . ~ t . o n e beds varios. At one rcnlis sp. and Lithoairot;;on. 1C1hitnc!li.placo, ot. t.ho hend ( f a smllll hronch gulch in 0 Mr. Girt.v states thnt t.heso faWI.S oresoutbw""t. direction from tbe Virginia Lodo scant and too poorly preserved to be Rssiprospect., t.he limostone close to the contact tn ony definite horizon, but he regllrdsstrikes N. 40 E. ond dips 42 SE., wherons t.ho os probably upper Mississippian.eontact. st.rikes about nortb. The limestone is Along t.he crest of the mnge north of themucbcontort .cd Ilndsomowhllt.metomorphosed. ond on its west. slope down to the divideFrom this POUlt sout.hwul'd the contact. oxtends t.ween Cherry and Vernon ereoks lie coalo'i1,g thho ?rcst of 1\ low south-sloping ridge, eonglomcfll,te nnd qUllrtzi te of pro-Cumbriaunt. .t e ,,dgo sUI'foee sink, bolow it., leaving oge, whose western dip suggest thnt.. theyonly hmcst.one, Imd t.hus proving t.hot. tho plane merly extended over t.he up POI' 1Iiississipof contoct. along tltis ridge dips west ot. a low quart.rite "n d that. the overthrust. OX tangle, away from t.ho dip of t.be limest.ono. os far ellSt.w"rd os the crest. of the WThe limestone at some ploces along t.be con tad 'fint';c Ran"e. Tbeir exact. trend in the Wis ovorloul. by quartzito and at ot.hers by shale . Tint.ie Ra;ge bowever con be determBoth t.hc olO(IS(.ono lind quartzite nro scutt.ered by detai led ,,:ork alone: roueh of theirat sovernl places along tho contact.. . faw being covered by disintegl'oted volc


17/22

SHEEPROCI\: "IOl.""XTA.lN'S. 439roc.ks and cure being necessary to distill!!uish ltho ligU-colored quart.zite members i n ~ tue a >out ]870, umounted to ubout 250 tons of 65pre-Cambriuu (1) from. b ~ d s of similar Ilppear- pel' ~ e u t lend oro containing n moderato pro-

I. ' I i ( " f Sportlon of ,silver. Tltis ore ws Sllljlpe.d toaDee in tuO upper" SSISslpplon 'J ormation. "'fhe stratigraphic und structmal relations of the LWt llSM, , , ules, lind to smeltel'S sout.h of Sllltrocks in t.he West 1'intic Rauge und the West IHe City. In ]S7I the property "'!Ill sold to, J o ~ b . LmV'J"euce ond nssociut.,s, who loin.d In ''fintic mining district ure shown in Il!!Ul"CS 46 b Id I , .109 t 10 1-[omunsviUe smelter in tile Tintic(p. 424) and 47 (1" 433). dlstnct. This enterprise f a i l ~ d , and "Lhe smelter'fhe 1l.gO of the o,'crt.luust is denrly !!l"eater dWas move awuy in 1872. Tho mine lutorthan thnt of t.he Tertiary igneous I"Od", bu t clln po


18/22

440 OR E Dt::P0 5IT .; OF l iT:\H .I " (IC"p op"n 0111 The oro hod v l l l l f t 70 fe c[, ("'OP, with shorl, drift , on t,hn onl l ~ r th e vem, . Thocopper stains , Some specimens ore of mug- thus for found sHml! bo(he", fnet ito ot,horn of hemol,it,,,, "nd hoth "uriet.i,," ono t,o n. few I,ons 111 weight" of h:IM 'en orcontn/n dissomilHlted gl'llinS and well-defined grade mussi,T". quorl,z associa ted with brovcinlets of pyrit.o. ?\o dlillcopY'1te WI\S reeog- fissures Il t, Ihe';r j u n c t , ~ o l l wi,th the mnill,vnizcd , Illid t he green co pper S La ln S may have ?etwccn t r ~ t , : " .. 1ho pnmary Ql'e lUllheen derivcd from coppcr in tho pynte. A IS chnloo pynte II I Ir regular pntc:he_ , ususmoll , hipmenl, in J!1l:J cont"ined 11 bcl.im is pYl'itized shulc nlong the honging wull mnngonese oxid e. Sewndary gungue mineof a porphyry diko. Oxidation has decom- are finely crysl-nllin o t,o chulcedonic quposed the pyrit,e nnd wnoontmted the ' iron and calcite."long the margin of t.!t" dike in the form of The Wa r Eagle chlim, II. short dis tnneo nolimonite in n. layer ranging from a thin film to eas t of the War Eagle No. 2, contllins cop6 feet t,bick A simila.r deposit of limonito are similar to th at just described cxcopt th'_hilS been opened in Il. prospect, hlllnel 00 tho lucks speculorito. The workings lire opeAlluh propert y efl-'lt of the shaft.. No ossnys by nn inclined shaft 200 feet deep sunk olof eithar are were obl,ained. Deposits of this th o hanging wall of a grnni te porphyry dt,ype mlly ba mi st lIk en for the went,heroo out- along which bunches of are were found, crops of 0. silver-lend dop osit, hut, it is improh- drift on the 200-foot level follows a vein treoblo thut ""luahlc silver-lend deposil s will b" l ing S. 70 W" which also follows n dike hafOWld in cit,hor shOll" or qunrl 7.ite. ing wall. A " ~ n z e from this level follo,,"

Closely reliltod to t,h" mnanetic are of theIron King mine is thnt,of I,he \viLr Ea"le No.2which forms It nort,h-BOu th vaiu " s"'hort dis:t,nuce to the east.. The vein is opened hy a

dip of I,he vein, which is said to expnnd doward to n \\;d th of 4 feet and to containare some of which assays 13 per cent copper 200 ounces of silver to the ton . The averwnt"nt is silid to be nbout 4 per cent coplind 16 ounces,of silver t.o the ton.


19/22

SREEPROCK ~ I O U N T A . 1 } ' ~ S . 441On I.he Wor. E o ~ l ~ No.3 prospret, eOTlsidpl'- 1 s ll1os(.J\, dellse nnd ehe I b t . II I1"" I' N0' . " ry U )9 w('< Cl'vst.n-obI.\" forther nort." " ."elll trer.( IlIg . 7,5 E. , hzccl around cMit.i!'>'. In n shullow pil. 200 feetand dIppIng from verb en.} to st.ccply nonh hns florl h of I.he slllcft. I.he vein consis!.s of quortz,been miMd from the sUlfnce. for lead or?,. bu t hurite, und galena. Tho bnri te forms u n e l ~ tbe workmgs w ~ r e not aceesslble when Vl slt.ed. work of pllll.V crystn.ls find th I df' . . ' , e qua.r z an

Oro seen on the SUI. nce consIsts of. glllenn.par:ly gillen" fill the int,erst.ic.es, impregnu t,e l.he bariteoxidized to c e n ~ s l t e , acc.omplllued hy w?,te erystnls, and fill crucks in !,hem. Pyri to Ilnd apotcbes of calammo, tI ht.t,le mlc.roscoplC snuth- few specks of zine bl,'nde ur" minor cOllstit,usonite, and brown and hluck st,nins of limo!!it,e ents. A litt.\e ccrusit.a ane! sel'onde.rv 'luort.zand Wild. The principal gnngllo l\t. I,he surfn.ec nre ttl80 p,csent.. .i, ('ulc.it,e in bnnded columnar mnsse. (1,r:J.ver- The mn teri,,1 in nncl CIO'C hli t he no"' ( jK"nrct;ne) , which ext.end in p\t\c


20/22

442 OR!; DEPOSITo Ok' cTAH.carbonate is most.Jy calcite, which inclosessmnllrhombs of ferruginous dolomite.Secondary ore minerals are l i m o n i t ~ , malachite, chrysocoUa, cerusite, and calamme, thecalamine indicating the former p r e s e n c ~ 0: IIconsiderable though minor amount 01 zmeblende. The second ary gan"uue mineruls aredruBY quartz, calcite, and amgonite in the formof tufts of needls on t,he secondary calcite.The different types of primary ore in the" 1903" mine include most of those found inthe ent,ire clistrict: The chalcopyrite-galenatype represents a transition from deposition atrather high to moderate temperatures; thefluorite nnd the barite-quartz types are believed to reprooent, deposition ot moderatetemperntures, and the bsrite-earbonate typerepresentg n still lower temperature, and, fromits structural relations, appears to mark thelast stnge of deposit on. Fnilure to find the/luOlite and barite-quartz types in contact prevents 11 stlLtement IlS to their rellllivo ages.The fluori te type hIlS not bcon f'Hmd in anyother mino in tho district.

ALLAll rn08P1-:CT.

Tho qllnrlz-ha,ritc-gnlonll type of ore is alsorepresented a mile north of the" 1903" mineby the yeins on the Allah property. Ono vein,4 or 5 feet wide, strik69 N. 1 O ~ E. Ilnd dips 80W. and is nssocillted with two ellSlrwest veinstrncellble fol' considerable distance by float,Very little prospocting has been done on tbeseveins. Besides tho well-defined veins severalsmall bunches of similnr composition Ill'e exposed on the surface and in the 198-foot shaft.Ilud .. ppetu to be local enlfirgements of tightfissures or at the illte1'9ectioDB of fissures. No,oro hns been mined on this property, but thewell-defined voins merit more Ilttention thanthey ha"e received. The presence of limonit.esimilllr to (,hnt in (,he Virginia lode was mentioned on pago 440,

SCOTI.\ ~ 1 n . i I . ~ .

Tho deposits in tho Scot,in mine, nt the northellSt base of the high limestone ridge, are a59ociIlted with a strong quartz vein that trendsS. 65 W. to the south of the Walker shaft andwith north-south fissures that have been followed f1'Om the shaft northward. The vein hasbeeu de,"elopoo by n few shallow inclinedshafts and by .. bout 450 feet of drifts, inac-

ccssible when visited; and the nnrth-sofissures ha"e beeu opened by a 150-foot vertshaft Rnd by drifts nnd inclines on tho .50 ,nnd t.50 foo t levels,The qUllrtz vein, cnIled the "nlue.Jny" vt,rends S. 65 W. clos(lly pt'raUel t{) a monzoporphyry sill, and probably connects witN. 15 E. vein which extends along the slope of the high limestone ridge and on wrthe Resun'ection (Prairie Bell) prospec.10Cllted, The Blue 'Juy vein dips 70-80.but its verticu! extent is not known. Winb"S benet'th it on the 50-foot level were icessible, and those on the 150-foot level hnot exposed nny prominent quartz veins. quartz of t,he vein varies from the fine-gl'll.repl"cemen t type to milky and well-cryslized varieties. It contains fino grains ofrite, and much of it is stnined with malncrazurite, light-green copper Ilrsenates, andunnamed hydrous lead arsenate, perhapsequivalent of the antimonate, bindheirnite,is, so far as seen, of low grade bu t has yielsome very rich ore from its hnnging-wall sThe principal ore shoot ig now representedthe" nonnnza" open cut, which extends d ownrd aC1'088 the bedding of a. shaly limestoknown as the "bonanza sha.le," into the unlying limestone. This rock, at the opendips 40-45 N" steeper than olsewhere onproperty and, together with the shattecharac.tel' of the rock, indicates consideradisturbance along the vein fissure. Theimpregnated the laminae of the shllly roekevidently reploced th e limestone below.sholy character of the rock mny have hud sinfluence on the gold content. (See p. 3Oxidation, however, further concentratedmetul contents, which rnn well in gold, siland lead. A short distance west of the "nanza" open cut the shaly horizon has bexplored by inclined shafts and dlifts, and csiderable silver-lead ore containing some copand up to 533 to the ton in gold is said to hbeen mined from them. 1 ' h c . ~ e old workiwere inacceEsible in 1913.The ore associated with the fissures trendN. 15 E. hus been followed from the 86-level, west of the Vvnlker shaft, northwarddownwa.rd below the 150-foot level. Thehorizon, 70 to 80 feot thick, is .in the limestbelow the "bonanza shale" and above n fgrained grauite porphyry sill. The prim


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SHEEPROCI; ~ ! O U N T A I N S . 443oro minernls are g ~ l e n n , jnmegorl,ite, pyri,te,arsenopyrite, nnd a lIttle c.halcopYTltc rmd ZIn Cblende; tho s " c o n ~ u r y mmcrals n r ~ ceruslte,'nalesite, hillohelmltc, " hydrous leilu nrsenntc,a h' I 'd' dimonite, uncI emn,tlte, p lUrmtlCOSI ente auscorodit.e. The prilnn!J gnngue min ernlg n.rereplacement qunrt.z, which h?s rc?laced l i ~ n f > -stHue and sc.alenohedrnl c"lelte; (,:"0 prmclpl\ls e c o ~ d " r y mineml is cnleitc in crusts nnd O.ttrhombohedrons.The main oro body begin' opposite the shafton the 86-[00t level, wh(,rc it consists of littlo galenfl nnd black re!,luC8ment quartz illa IDMS of 30ft hemiltite. ),Iinernlized gruundVIlIS worked from this point nurthward for 170feot to II. cave which cOlltaiJled severnl loosoboulders of high-grade ore. A small stope extends from the )vest end oi the cave, followinga northerly fissure down to the 150-foot level,below w\,ich small amounts of ore h.wo boonfour.d close to the fissura. A short distancenorth o'the CII.ve, at the top of No.6 mise, a

soluble 2.4.3 to 9 pCI' cont, zinc 1.4 t.o 3.:3 per('ent , sulphur 0.7 t.o 3.8 per cent, "lid spei'S' 26 to41 per cenL The pcrcent'lges of sulphur showthnt most of tho ore was oxidized. Some"boulder" ore from t.he cave is s!lid to hllvecontained 60 per cent lend I1nd 200 o\l\lces ofsilvcr to the tun, and the oxidi>'l'd al'Senop),l'iteore from S10 t.o Sl5 of gold to the ton.The changes in minel'al cO ITI!,osition of thoore imply that the nOl'thern pttrt. is f"rthestfrom tho source and th"t the meh,l conkllts ofthe ore d",,'re.lse in value nOl'thwllrd, espccinllyus very little oxidation has t.aken plac.e belowthe 130-foot level. From th is it muy be infened that tbe ore solutions Cllmc from t.hesoutb, possibly from the "Blue Juy" ,'ein;but nu wnllection with this vpin hilS been cstublishe


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444 OIlE DEPOSITS OF UTAU.on ucorrespondingly smull scale, Ilud undc.r cou-dit.ions thllt. did no t favor the ",oneenl.rutlOn oCde.p0 5ition in II few main c.hllnnc\g.

The work done justifies tho. coue.\u.ion thlltwith more fnvor(;blc transportation facilitiesth e district co uld ",oint.in 11 SDl"ll stcftdy output., bu t thnl. undel' present conditions there islittle hope or Mendy product.ion.

DESERT MOUNT,UN.Dr G. F, LOUOIlLlS'.

Desert Mountnin, or, more uppropriutely,the Desert lIills, include 11 cluster of low bl1repeaks which lie shout 12 miles southwest of theWest Tint.ic milling district.. The nearestrn.ilro.d St. ..tiOIl is Jericho, nbollt 20 miles to theens!.. (See fig. 46.) 'fhereis nowIlter ut Desert.Mountniu; lhe ueores\. supplies nre nt JuddCreck, 8 miles north-northwest, on the rond(.0 Simp,on MOI/Htllins , nnd Ill, C1,ol'r)' Creok intho Wesl. Tiutie dist.rieL, !2 milt1s cusL.

GEOLOGY.

to L h ~ ,.hove minerrus contuins It smull peentllge of muscovi te. I t nlso contllins phecrysts of feldspIII' and qu,u'!.z, few of whichCOIL_picuous. Many of th e uplitic dikes hCOllrse-grnined pegma t.it.ic vnl'intions whgl'llde into massive qual't.z veins. Severol sqUIll'tz OCCUITences outcrop "long the ramong the low hills just. north and northeof the Rockwell shaft, but none nrc h..nough t.o be of flny economic interes t orshow nny promising indication, of mcontents.

'1110 dinhllse is dlLfk gree.nish grny ,md hifine-gmined ophitie fexture, except luongdilw margins nnd nurl'OW offshoots, where blnck and dense. Th e visible mine.ralswh ite feldspnr in short rodlike grains, insoft. durk-green chlol'itic m a t ~ r i n . J . . Therc'Suggest.ion of porphyl'jtie texture in placeschloritizerl durk m llterial (pl'esUIDnbly nugformillg smull phenocrysts. ~ l i c r o s stushows the feldEpllr to be principal ly plagiod(An,) accompo.njed by I l litt.le or(.hocII

Only t.he westall fnco of the mountn.in wns The composition of I.he fOl'mer, moro sodic tvisited. The rock hore is mostly lL light-gray in the averngo diubllse, and the pr('S,'nco ofgranite cui. by II few diabose dikes. Apophyses lntter are chnmcters tcnding t.owtlrd thosefrom the gronite nre intrusive into 11 dark monzoni te.qual'tzite wbich hilS not beeu studied closely, ' Both t.he t.opogmphy und dist.ribution ofbut. which presents t.he same dllrk colors on qu/Ut7ite and gronite suggest f'lUl t.illg, !'Swellthered sminces IlS does the pl'e-ClUJ1brinn( 1) cinlly 1U'0und the vnIley just mentioned, butqUIll'tzite serit'S of the S)'ooproek Mountnins fnults were proved. Th e grunite is t.horougand t.he sout.hol'n SinLpson ~ [ o u n t n i n s . The fissured in seveml directions, the princiqUIlM.zite is exposed at t.he southern I1l1d s y s t ~ m s trending north-south (dipping 45-northorn end of the mount.nin .1nd in low knolls W.) IlIld eust-west (dippillg 60-65 N.) .which ext.onrl to tho northenst. Detritus from bot.h of those syst.emS sheet. joinl.ing is vthe principn! vulley which dmins tho southern conspicuous. 'Another strong system htls gp"rt of the mountain nre" contnins I t Iltrge t l ~ dip and nMr thc quartzite IlpprOlcimunumoor of pebbles of volcnllic rocks (mostly pnrullels tho int,rusiva contuct.rhyolitic), bu t no oxt.l'llsi\' e rocks were seon inplace. OR E DEPOSITS.

Tho gronite is light g"'), nnd mnges in '111e ouly k n O " ~ l import.lmt. oro depositexturo from ..von grained to porphytit.ic. Tho Desert ]'[OWlt"in is the vein followcd bymoin hody is IUllch e.l'umblod ou the surface, Rockwell inclined shltft, ne ..r t.he northwis medium grained, Ilnfl in places contains end of t.he mountain, south of '" g"oup ofphonoc.rysts of n!kalic feldsplU' (ruicl'oC\ine) f,nd foothills. There lire n few other prospectsof quurt7. hill nn inch in ditUllet.e,. Its prwci- t.he vicinity, but only" litt.\e work hIlS hpIll milleruls I1re wbite foldspur (both plegio- done on them. The vein follows 11 nort.h-soc\nse Rnd ,llierocline), gray glossy quar tz, und sheeted fi,;sure 7.OUO, which dips 60 W. Tblllck to brownish flakes of biotite. Another ouuropof copper-stained rock is 6 to 8 f e e t w : it}"PO is nn n p l i ~ e which. forms dikelike IlIld I t is plwtIy covered by durop d ~ b d s bu' ~ T e g l l l , , : r masses i l l the mllm body, to which it is oxposed for at leust 50 feet south of the shos,m,lnr III color but. IS much finer grained. I t is 'which he"ins iu Ore Th e cliffs howeve.r,fresh oven close to the surface ILUd in nddit.ion I .he spur j ~ s t north th " shllft, :uthough th

Sheeprock Mtns Pages from USGS PP-111

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