Show THE GENESIS OF GOLD BUTTE LOCALLY KNOWN AS GRANITE MOUNTAIN A stranger on arriving at gold butte would doubtless be unfavorably impressed by the unique surroundings to the north he would look out on a group of faulted and sharply tilted limestone ridges rising from the west to a height of 1500 feet turning to the south he would be face to fadi face e with a granite mountain about feet high he was roughly sketched in relief As an aid to clearness many of the details were omitted and while its execution reflects no credit on the maker the physical conditions thus sharply illustrated on that portion of the map are explanatory of those other conditions which as a rule are indispensable to the presence of the precious metals A about alb out 80 beet E cross section of field fromA from fr om A B be 8 c Q M mala ma a la hife position of burie buried d cinie L idestone etolie loocin L aoki a southwester I 1 y v T vae at e x 0 C cl so c 01 e voy rca A 17 s y 0 v C C 61 k s I 1 7 1 T r T I 1 F I 1 I 1 F would instantly note the fact that the ragged dragged crest is surmounted with giant bowl ders and that the mountain side is thickly studded with them the stranger would also note that from the base of gold butte I 1 granite mountain well out towards the lime escarpment to the north the flat is i strewn with great boulders bowl ders of granite too broken too jumbled up would no doubt be his mental verdict the following discussion of the genesis of gold butte will illustrate the of forming conclusions as to the merit or demerit of a mining district without careful investigation of the details that form the letters words and paragraphs of its geology it is impossible to discuss the origin of gold butte independently of the general geology of the adjacent country in order to avoid tedious descriptions and to make plainer an otherwise somewhat complex subject a map and several diagrams have been introduced the locality to be discussed is the st thomas mining district and occupies the region in the angle formed by the junction of the colorado and virgin rivers and Is situated about fifteen miles north and east respectively respectively from those streams in the southeast corner of lincoln county nevada its altitude is about feet above the junction of the rivers before mentioned and feet above sea level in order to give a clearer idea of the stupendous faulting and tilting of the limestone to the north of gold butte that section from the highest point on the eastern portion of gold butte the western rim of the vast colorado plateau is visible at a di of about twenty miles illes to the east and southeast the limestone strata of that deeply gashed plateau are as horizontal as when first laid down on the floor of the lower carboniferous ocean to the northeast in the vicinity of the grand gulch and savanis savani vei vvhs ON JL atohi to ld 8 0 0 0 fe beai tt B same as ae Plate Plat lAjter elASter L can and ca ov over cr I lour ow of schist lt w X 1 1 X 4 x S I 1 v 4 x X X X 1 1 1 X 1 1 is 4 T w 4 T 1 t V 5 T T copper mines the limestone is also in bedded form across the colorado river to the south the same bed of limestone is in evidence in fact there is ample proof that the lime stone of the colorado plateau when lifted above the ocean extended north to caliente and west to the california line gold butte is the north extremity of an eruptive uplift that broke through the limestone and completely buried it over an area of at least fifteen miles in diameter the foregoing description will enable the reader i to intelligently follow the consecutive dynamical events that from profound depths forced upward the material and built gold butte that profusely and systematically seamed and fissured its rugged sides and injected into each seam and fissure e a stream of gold bearing solution it is generally agreed by the masters of geological science that the closing centuries of the tertiary age was an era of worldwide mountain building and to that era may be safely credited the first serious disturbance tur bance ance of the earths crust in the vicinity of G gold old butte it will not be a serious tax on the readers mind and will save an engraving to 10 imagine a flat bed of limestone prior to the disturbance just mentioned the forces that wrought the tremendous changes of level in the vicinity of gold butte were not explosive A large area t to 0 the west was slowly sinking producing an equivalent equi valen t uplift in the region now known as the st thomas mining district under the enormous strain the bed of limestone was broken northerly and southerly some fifteen miles west of gold butte and formed the depression now occupied by the virgin river the line of fracture and faulting is now marked by a range of ragged volcanic mountains to the north of goll goh butte about two miles a section of the limestone represented by lime mountain was broken and forced force upward fully feet and tilted to the eastward toward which point the strata descends at an angle of about 70 degrees along the base of lime mountain as shown on the map is a belt or reef of probably devonian quartz ita with an inter collated belt of shale from M ra si r 4 ir V aa 4 x t A ar ir x r aa 1 F 47 ap 4 M 7 C N C 7 T 7 R 1 74 f I 1 4 17 a ol 01 v ce V t tunnels F 17 ji 0 ct de 71 re ct i on wa she s 00 Y 0 43 CUL Z IF 7 Z lines 0 S R 41 L IX i 7 1 U lie birdseye view of gold butte bulte section lincoln county nevada the east face of lime mountain to the quartzite along its west base balse is fully two I 1 m miles iles and clearly represents the depth of the limestone and approximately the extent of displacement the between the quartzite and the limestone mountain to the west Is a dyke of eruptive schist which occupies the westerly line of faulting the strata of the finestone fim limestone estone just east of the quartzite reef dip easily at fin an angle of about 45 degrees while the reef goes down on a dip of 80 degrees and suggests the probability an A shaped dyke of eruptive material forced up within or near the contact th tb producing the of dip B tense metamorphism of the limestone is everywhere in evidence and wherever the strata descend at sharp angles volcanic solutions worked upward along the cleavage planes now nov marked by the presence of dark lava like material the ascent of the molten granite the schist was broken into small and large boulders that were appropriated by the former and in the upward rolling movement were rounded smoothed and distributed through the magma that the granite mass A airola reemt N 2 A after f fter ter coulon of J Grap granite tite V e N xo aln n cl i ss c c LL rin 0 JT c e I 1 T L ino LZ has 1 p V 4 c W lh 0 F 7 ia at fkr afe ishi ant ta r L iii 1 ti inai in fi y i Z ae 7 Q 7 1 i I 1 t r 7 N 7 T 4 I 1 N 1 T 7 R the position of the limestone beneath the schist and granite south of the fault escarpment carp ment to the north of gold butte can only be inferred there are however certain surface conditions that will enable us to arrive at reasonably correct conclusions the attitude of the colorado river at the old scanlon now griggs ferry is fully 2500 feet lower than gold butte between the ferry and the fault escarpment just north of gold butte or a di distance of fully fifteen miles the limestone is deeply buried beneath eruptive material in its descent of more than 2500 feet from the fault escarpment to the colorado the limestone is doubtless in a highly faulted and folded condition but for the purpose of illustration and the greater ease of map making the limestone is represented as descending towards the south in the form of terraces see plate I 1 L the fissuring and faulting of the limestone was followed by an eruption of schist which in condition was forced up through the great fissure represented in the lefthand left hand portion of cross section diagram marked plate 2 on its exit from the fissure the schist chist flowed southerly and northwesterly ever building higher over its channel until the fhe forces that had impelled impell dd it upward had been exhausted while the schist represented in plate 2 was cooling and solidifying deep seated forces were gathering for another outpour out pour ing of eruptive material from a depth of more than 2000 feet molten granite moved upward along the channel opened and enlarged by the previous flow of schist in was more viscid than the previous eruption of f schist is amply proved by the fact that it built upward over the great fissure from which it was emerging and now appears in ward several hundred hundred feet above the level of 0 the adjacent country the map and cross section diagram marked plate 3 show granite buttes of small size occupying positions out on the flat As before stated the sides and bases of gold butte are thus marked with thickly strewn boulders bowl ders of enormous size and that give to the mountain an intensely rough and broken appearance but on closer inspection spec tion the jumbled up condition is found to be ideally perfect and regular in its system of strong and deep seated fissuring with one exception each of those fissures indicated on the map has a general strike of north 25 degrees east and which is in exact harmony with the strike of the fault escarpment that passes to the east of lime mountain in addition to the principal fissures shown on the map and cross section diagrams there are at least a half dozen minor fissures occupying positions between the larger ones or separated by only fifty to feet of intervening un fissured ground there are also shown on the map and cross section diagrams other fissures marked fractures and which along their southerly prolongation become highly mineralized those fractures are marked along their strike by small granite buttes that are cleft vertically forming bands some two or three feet in thickness ss the halftone half tone herewith is from a kodak picture of one of those buttes about feet west of the exposed t IM A 51 X N IN V 40 view of gold butte mother lode miner standing near the center the form of a butte whose altitude above the flat is from to feet in other words gold butte or granite mountain as it is locally known is a great dyke projected up schist to the east that those buttes are in place is beyond controversy there are at least a half dozen of those fractures between the escarpment to the north and granite spring fissure da each ach has a strike of north 25 degrees east or in harmony with the strike of the fissures that traverse the north side and base of gold butte and with the general trend of the fault lines to the north the granite spring and lone star fissures are marked with vertical bands from three inches to six inches in thickness the cleave age being perfect fact the minor portion of the magma that built gold butte came up from the west while the major portion ascended vertically ti cally and which gave to the mountain its peculiar structure as illustrated in the longitudinal section herewith fissuring of the mountain was impossible until the granite had sufficiently cooled to permit of the maintenance of the fissures that some portions of the surface had entirely a i r 1 4 1 r W A fissured granite butte the student of geology more particularly win will be impressed with the evidences that so strongly attest the profound depth and permanency of the gold butte fissures the only speculative fea feature cureto tu reto to be discussed is involved in the th source from which was derived the material that formed the fissured buttes north of granite spring it has been pointed out thit that the limestone in the vicinity is more than feet thick or a depth of fully two miles the uniformity of the fissuring indicates that the fractures extend downward through the carboniferous limestone and very likely much deeper force follows lines of least resistance and it is impossible to believe that granite I 1 magma mag ma traversed those narrow fractures upward a distance e of more than two miles and built the small buttes butte s that are illustrated in plate 3 and by the halftone to n e herewith it ft is less than feet from the fissure named the mother lode out to the fault escarpment to the norih norh therefore the solution of the problem becomes easier and more in harmony with the well known operation of dynamical forces to believe that the molten granite impeded in its upward flow by the enormous weight of the mountain sought the greater line of easement by opening a passage passage to the north through the limestone as illustrated in i plate plat e 3 s solidified fled prior to the fissuring is proved by the fact that veins dip under some same of the larger jarger boulders bowl ders and reappear on the other side and with persistent continuity of strike traverse several thousand feet the fissuring was succeeded by the ascension of hot acidic gold bearing solutions along the fissure formed channels and the veins of gold butte were completed alan along with the atoms of gold atoms of iron were I 1 that under a good magnifying glass is T re solved into iron crystals accompanied by i specks of the yellow tiny metal this fea fp ture is an almost insurmountable obstacle to t sorting while generally combined with wit iron visible gold is not unusual in the th white quartz and is invariably associate with manganese when that mineral is pres ores ent while the granite spring fissure yields gold from iron rust that occurs in thin sheets between t the e vertical bands it is val ueless except for the pure soft water it affords A special feature of the other vena ve n is that the altered granite invariably carries gold in good milling values and is an important factor in the filling of the mother lode which is deserving of special notice like the granite spring and lone star fissures the mother lode is in banded form the bands ribbon like structure stand nearly vertical the slight difference of dip between the outer bands indicate an increase of thickness with depth the vein is fully twelve feet wide on the surface ani can be easily traced by its vertical bands so sharply in contrast with the massive coun try rock the accompanying photograph looking northeasterly furnishes a faint fidei of the remarkable lode the lowest assay of the white quartz no visible iron cr gold gave returns of gold old no silver A s selected e sample of quartz showing the characteristic act iron crystals gave returns of gold and trace of silver samples of iron stained quartz a special feature 0 of the mother lode gathered haphazard from tons of float below the vein yield gold some of it quite coarse by the panning process it it however too low grade to ship the granite country rock contains an unusually large proportion of feldspar the larger crystals of which are generally ular having been rounded by the move movement met of the matrix in its exit from igneous depths palitos pa I 1 loh longitudinal al aa GRANITE N mountain ce cedar 13 basin cusin s side 1 de L Loo lookia 0 0 o k kig inq N north ort K JA 9 L L acco structure also appropriated by the solutions and combining crysta crystallized into those forms in which iron is the principal compound containing nuggets and thin flakes of native gold are frequently encountered in all of the gold butte fissures and are among the most unique and beautiful gold specimens in existence the seams in the quartz are usually filled with streaks of iron fluorite is also present especially in the vicinity of the fissures small rounded pst bles of altered limestone are occasionally encountered in the debris from the vao tain and while not yet conclusively proved there is good reason for believing th they eyvere aers a at t one time embedded in the granite the nevada gold butte lone SW stor will be mother fissures lode and intervening pierced by a crosscut cross cut tunnel now in a distance of about feet from portal to face the tunnel is ever an interesting study after the first fifty feet red iron ifon |