Show ORE CHANNELS CH by D P at east tintic gintic in the property of the east tintic gintic de company in a small limestone area surrounded by rhyolite is a mineralized outcrop underlain by a small ore body from which over 50 carloads of silver lead ore were mined and shipped in earlier days evidently this ore body incited development in neighboring ground which led to the discovery of the famous ore bodies of the tintic gintic standard mine this mine has today what is in all probability the largest proved silver lead ore bodies in the united states naturally the discovery of this immense and rich ore mass incited developments all over the east tintic gintic area the east tintic gintic mining region except a few small limestone areas is overlain by a thick flow of rhyolite a clayey rock that was laid down prior to the period of ore deposition evidently due to its clayey nature the fissures that entered this rock were soon obliterated so that ore solutions could not penetrate it and hence veins are not traceable at the surface obviously then the prospecting for new ore bodies is speculative and should depend in a large part on i a detailed study of the district especially embracing the iro probable bable location and habits of the principal mineralized fissures the ore channels the geology and ore deposits of tintic gintic have been well described by careful and competent observers in the publications of the united states geological survey and only enough of these subjects will be gone into here to enable the reader to obtain a comprehensive picture of tin tics bics ore channels th the tintic gintic mining district embraces an area roughly five miles north south by six miles east west on the east and west slopes of the central portion of the east tintic gintic mountains in juab and utah counties about sixty miles south of salt lake city utah the first discovery of ore in the tintic gintic district was nade de in 1869 in the sunbeam mine along a fissure in the nion soon after that other mines were opened up in this ais rock and rich shipping ore was found cropping out in the ie limestone area north of the onre onte since then the growth of the district has been steady for over fifty years lt it has as been a continuous producer mo most t of the old mines are e still shipping ore and today it ra ranks n i ks as one of the main ire re producing areas of utah the main ridge of the east tintic gintic mountains curves and wobbles in a general northwesterly direction through gb we e heart of the mining area arca and the crest of this ridge es tab blis lishes hes the boondry line of utah and juab counties ero sion on has sculptured the district in such a manner that the typography Po graphy is rather rugged tintic gintic valley to the wp hect has nas an elevation of feet goshen valley to the east is about ottoo feet high while portions of the main fridae reach ovations elevations of over feet and the principal peaks along this ridge attain altitudes of feet or more the longest gulches and canyons have a northeasterly trend and in the main follow lines weakened by faulting water vater is rather scarce there are no perennial streams in the east tintic gintic mountains springs and wells in debris filled depressions in the impervious volcanic rocks furnish the water supply range of formations erosion has exposed a great range of formations in the tintic gintic mining area they consist of sedimentary intrusive and extrusive rocks the sedimentary rocks exposed belong to the ca cars 7 brian ordovician devonian and carboniferous system s the tintic gintic qua quartzite of lower cambrian age age b is the lowest formation shown it extends along the west base of the th range and is over feet thick overlying tile the are about feet of limestone ranging in age from middle cambrian to upper mississippian the main limestone mass lies east of the quartzite and north and northeast of a large intrusion it is is irregular in outline and it covers an area of about six six square miles it is bordered and capped to the north and east by rhyolite and tuffs and flows so A few small isolated patches of limestone crop out in the rhyolite area the lime stones vary in color texture and composition they are from light gray to bluish black from fram dense to coarse grained and are alternate beds of sandy dol and pure lime stones the lime stones in contact with the are more or less metamorphosed A zone of metamorphic limestone extends continuously from tile the main body to the carisa stock and farther northeastward and disappears beneath tile the rhyolite I 1 flow the igneous rocks in the mining area include nion stocks and dikes a few small rhyolite dikes and rhyolite and tuffs breccia brec cias sand and flows there is no evidence of the age of the igneous rocks in this district but similarity of these rocks to those of known age farther east cast suggests that they are tertiary the wain main stock is exposed north south and cast of silver city it is rudely elliptical in outline and covers miles A minor nion an area of about three square stock lies northeast of the main stock near the carisa mine bodies ot of small of farther northeast are outcrops the while these dik elike bodies are small at and iron king sho show A surface mine workings at the zuma that they are much larger at depth great importance of the is the latest known important intrusion the tintic gintic district and it is therefore alit kusiv into all in the is is other rocks with which it is in contact behe economically the most important rock in this area for the ore deposits occur along veins in this rock and are also found in the adjacent sedimentary rocks and porphyries ries along fissures faults and fracture zones intimately asso socia ted with the that the exposed south of mammoth is a large intrusion only partly exposed and continues northeasterly for several miles not far beneath the surface is strongly supported by the following facts 1 metamorphism P hism of the lime stones along 6 a zone striking northeast from its contact with the main main mass of 2 the small stock of near the carisa mine northeast of the main stock 3 the small dik elike bodies of propping cropping out in the rhyolite area several miles to the northeast of the main mass and which as proved by mine workings are much larger at depth 4 and indications of doming with a northeast trend in the limestone area of east tintic gintic roughly parallel to the long axis of the exposed mass and to the major set of fissures developed therein rhyolite flows cover the northern part and nearly all of the east tintic gintic section of the mining district no ore has been found in this rock evidently Evid etly due to its clayey nature the rhyolite acted as a dam to the mineralizing mineral izing solutions structural features there is evidence that the large stock of south of mammoth has 4 t 14 44 4 t iz W U raz OZ Q h va YO 7 na on 0 L mes 17 7 rn 01 s ren v 9 it N 3 ea ton to J V v wv W ilk sr hyo ta TIC T RD al becia A 1 4 Z Z ve J jrsn F 17 V jita 41 L 0 X tr ah q OH 4 L ali N U Z ri 0 o D IZ 1 I NILE 0 7 geologic map and section showing Tin ticH cm ore channels domed the sedimentary rocks and it is probable that sediments and lavas at higher horizons now demov removed ed by erosion were domed over this intrusive body furthermore doming t with a northeast trend is indicated in the lime stones of east tintic gintic folds are generally largely concealed by the volcanic rocks rock s but a large synclinal fold in the west part of the limestone area north of the exposed za nite intrusion is fairly well defined this syncline trends north and pitches northward the west limb dips very steeply to the east cast and includes th the C four ore channels known as the gemini mammoth go godiva diva and iron blossom th the e east cast limb has a relatively low dip farther east from the axis of the syn syncline cline the beds lie nearly flat and then turn gently upward and assume a general northeasterly strike indicating an structure trending northeast early fissuring an and d fati faulmi lint 0 are other im important t structural features in thed the district is most of these disturbances tur bances took place e pro prior r the per period iod to an and d during of indru intrusions there has also be been en consid considerable erable fis hs suring and faulki faulting subsequent of 01 intrusions to the cintr the the fisser ing and faul faulting fing in t ane lie ad and it in the ao jacent rocks caused main ly by coo cooling ling subsequent fractures the the in t to intrusion and in the rocks within the limits of influence of tile the nion have a northeasterly trend and are roughly parallel to the lono long Z axis of the intrusion i they hey are plainly due to contraction strain 0 originating i rigina ting in the intrusive mass subsequent to its consolidation contraction of the not only caused the fissures but also necessitated settling 6 along some of these which then developed into faults generally of small displacement there is evi evidence lence that this faulting continued after the period of numerous of these fissures and aults attained great depth they then became lines of least resistance to the upward pressing 6 ore solutions rising from the plutonic hearth of the magma the ore solutions penetrated these shrinkage fissures and faults and their hasure connections in the adjacent rocks along their journey they deposited ore and gangue minerals by replacement and allin tilling b along 6 the most favorable places and effected other changes in the wall rocks importance of shrinkage features the shrinkage fractures and faults in the and in the adjacent rocks are then the mineralized and mineralizing mineral izing fissures and hence they are economically the most important structural features in the tintic gintic district this assertion is sufficiently proved by the fissure veins in the which obviously were caused by shrinkage are mineralized and contain valuable ore deposits furthermore there can be no reasonable doubt that the complicated zones known as the gemini mammoth godiva and iron blossom ore channels which so far produced the bulk of fintics cs ore are also due mainly to the contraction of the intrusion for all of these ore channels are intimately associated with the mineralized northeasterly fissures in the two of these ore channels the godiva and the iron blossom follow northeasterly fissures which had their inception in the nite across the contact and beyond through the metamorphic limestone without plain bedding to tile the sioux ajax fault almost without interruption and with no change in strike from here they bend northerly and follow fractures which practically coincide in strike with steeply dipping limestone strata probably the steeply dipping limestone bedding planes being the line of least resistance had something to do with the change of direction of the ore channels from northeasterly to northerly moreover Afore over the fracture zones constituting the four ore channels are continuous and their continuity is not much influenced fluen ced nor interrupted by older fissures and faults which they cross hence they are the latest and the last dis ingui structural features in fintics cs mining abreh area t resulted mainly from contraction due to cooling of the nion the observed facts show that the primary ore and gangue minerals were formed by hot solution rich in silica barium and various metallic sulphides sulp hides and that the wall rocks of fintics cs ore bodies are lime stones dolomites porphyries ries and quartzite and that the rock types in inclosing losing the ore bodies in the west part of the district so far r the most favorable for ore deposition appear to be relatively pure dolomites and lime stones the first shipping ore in east tintic gintic was discovered in the ine herkimer herkim er formation the rich and large ore mass of the e tintic gintic standard tan dard mine lies in the ophir formation P and tile e profitable ore of the iron king mine occurs in a vein in the e tintic gintic quartzite the herkimer Herkim cr the ophir and the antic quartzite formations at tintic gintic were always considered of no economic importance until the discovery of pay ore or in the tintic gintic standard and the iron king mine glancing over the whole known mining fields it appears that rich and valuable ore bodies are found in quart granites goranites gra igneous rocks of all kinds pure and impure lime stones and sandstones except in rocks so plastic and clayey that openings cannot exist at all or only for a short time thus preventing the penetration of ore solutions it seems to be a fact then that alter after ore solutions once penetrated a fissure that bolens volens ore deposition must take place in one place or another along this fissure irrespective spec tive of the character of the wall rock types ore deposits vary in the most remarkable fashion in some cases where the vein walls are readily replaceable the ore solutions penetrate the wall rocks intensely and in favorable places build up large ore masses with irregular and indistinct limits in other cases where the walls are not readily soluble and replaceable the solutions deposit ore over a long stretch along the vein replacing as much material as they can and fill and impregnate pores cavities and other interstitial spaces then there are cases especially if the ore solutions are highly concentrated where they fill with ore clear cut veins without bringing about a conspicuous change in the enclosing rocks the indispensable features in the formation of ore bodies are fractures fissures or other openings in rocks penetrated and mineralized by ore solutions thus composing veins to be sure tempera temperature ture pressure con conditions di eions and the chemical makeup make up of the ore solutions and also the physical chemical and structural features of the wall rocks all function more or less in ore deposition and in order to mine mine intelligently and on account of their great economic importance the features in a mine or in the mines of a district that localize ore deposition and form ore shoots or bonanzas Y should be understood as much as is possible the evi evidence dende having a bearing on fintics cs ore channels makes it clear that the northeasterly trending intrusion originated the ore channels that the ore channels occur along fissures in the and in fissures and fracture zones in the adjacent rocks within the influence of the that the principal ore channels are along fissures caused mainly by the cooling and contraction of the nion magma that the ore channels belong to the latest structural features distinguishable in the district and that the ore channels when not diverted trend northeasterly and roughly parallel with the long axis of the intrusion finally if the observed facts fact are correctly interpreted and I 1 believe they are it follows of course that in t the lie east tintic gintic mining area after a shaft has penetrated the sedimentary formations prospecting for the ore channels should be south southeasterly easterly n northwesterly orth westerly the shortest distance to the principal veins |