Show NATURE AND ORIGIN OP OF 01 ORES E geologists differ as to the method of much has bas been said and written of the precious us metals of mercur or camp floyd mining district tho the nature of the ores oreg from which they are derived the manner of their occurrence and genesis of the same on the most of these points those who h have e made m a practical study of the district agree it Is that class which looks into geological ecological conditions from rom an ultra theoretical and scientific standpoint only that has disagreed one thins thing in which however all concur li Is as ail to the strike and dip of 0 the great croat zone and the immensity of the deposits alons along its sinuous but practically unbroken course from tile the base ot of lion hill and lewiston peak southward tor for a distance of eight miles nor la Is there any marked as aa to the nature of the ores or the multiform ous forms forma in which they appear DIFFER AS TO ORIGIN it Is upon their origin that scientists differ a matter to which the practical miner Is profoundly indifferent so long lone as athe the precious metals are at hand with a process for their successful extraction one school contends that it Is in con bly while the other Is a as it fervid ln in its contention that with tire th testimony mony at hand band it could not be 0 otherwise ther than sedimentary one of the most exhaustive trea treatises tines upon U the matter of geneale ge e neals Is t that hat apon which was a few months ago ha handed tided down through the department of the interior consisting of deductions drle n by prot prof samuel franklin emmons emmona from researches made by J edward spurr this treatise appears in an a n extract from rom the sixteenth annual report of the department nit upon the miners mineral resources of america and entitled Econ economic orrile geology of th the e I 1 mercur mining district TWO ORE BEDS to mr R C hills of this city the report acknowledges its indebtedness tor for a chapter on the physical conditions existing at 01 mercur and quotes him as a follows follow two ore bearing beds about feet apart exist elet near the middle of a great adries aeries r of flim estone strata the lower of these beds consists of quartzite of dark limestone and porous carrying carryl nc silver with bomea some antimony n and copper but no gold an and Is I 1 cal calad tho the silver ledge the upper known as the sold gold ledge la Is a zone or bed decomposed sometimes bleached sometimes red or yellow limestone and shale which carries over considerable areas and cinnabar together with a low but comparatively un uniform I 1 form percentage of 0 gold cold but no silver PERIODS OF the alie main conclusions arrived at by mr spurr with regard to the deposits may be summarized as aa follows followay fol lowa there have been two distinct periods of 0 1 in n this district luring during the first what Is called the silver allver ledge ore was formed and during the second the minerals of the gold ledge were deposited 1 in n each period t the h e m minerals 1 n e ra 1 s c constituting 0 n st i t u t I 1 ni z I 1 the hl ore were d deposited e po si t e d r mainly n al n 1 y a alon 1 0 n g t the he lq lower ver contact of a porphyry pot phyra sheet where it a somewhat porous or zone had been formed by the intrusion of tho the igneous material which the mineral izing solutions reached through fractures or fissures extending downward from the respective sheets PRINCIPAL VEIN MATERIALS the principal vein materials of 0 the tha gold bold ledge ledee are alear re cinnabar and pyrite with sold gold which was waa probably deposited as telluride with them aro are associated barite and calcite presumably of earlier formation together with gypsum and other secondary minerals the deposits are found mainly at tho the intersection of certain zones of oc northeast fractures frac turea with the lower contact of oc the middle of the three porphyry sheets and reach a thickness of twenty feet or more chining out to little or nothing away from the fracture fla some of the fissures tire are still open and show no evidence of filling or erosion by circulating waters these fractures cut across the silver ledge and as a rule nil do not extend above the gold lodge PROF conclusions after digesting tho hi report and reasoning irom from it prof pro emmons offers tho the follow colloy ing conclusions the period of the gold ledge since it was separated sera rated from that thae of 0 the sliver silver ledge hy by the formation of oc the northeast fractures must most havo have been later than crustaceous crusi accous or as lato late as tertiary its possible connection with or dependence upon an unknown body of recent eruption rock Is 1 too remote to justify an attempt to fix the period with more definiteness tho the theory that metallic minerals have been brought into ore deposits by tu fu marollo carolle vapors which Is the one centrally generally entertained by geologists of 0 the french school Is one that many writers are not noi inclined to look upon with favor the more practical anti anil tangible conclusions which may be derived from this investigation are that in fit searching tor for gold in this district it Is necessary first farst to learn to recognize and identity identify the porphyry sheet in the field in its many and varied forms of alteration and then to follow that rather than any given lead in the limestone series second having traced the gold ledge porphyry sheet one should follow the intersection of this sheet with the principal zones of 0 the northeast fracturing and prospect the ground downward along these intersections and in their vicinity it may be remarked that it Is probable that the oxidized ores susceptible cep tible of ready reduction by the cyanide process will be found to be confined to a zone of rock within a 41 very limited distance front the surface and that explorations in depth will soon reach sulphide and telluride ores which may have to 10 be smelted smelter smelt ed it Is however fair to to assume burne that these ore bodies are likely to increase in size and richness with depth and ores may be found which are arc sufficiently rich to be mined at a profit in spite ot of the difficulty of their reduction MR SPURRS THEORY presently Present lB lg his theory upon the genesis of camp floyd ore bodies mr spurr says the part played by gaseous agents in the formation of 0 ores has been little regarded of late considered as a gold deposit of mercur Is certainly unusual asua usua for in most deposits the gold has haa been undoubtedly precipitated from circulating cu waters however considers that vapors may have formed gold deposits as well as those of 0 the other metals and it teems seems probable that the conditions governing the deposition It loii of the telluride ot of gold are different front from those which chich bring about the concentration of the native metal 11 in concluding his deductions mr spurr pays fays the of the gold ledge probably took place at a distinctly later period than that of 0 the silver ledge and the general nature of the phenomena indicates that the agents were gaseous rather than liquid that they ascended along the open vertical fissures probably from some rome body ot of igneous rock below be lowana and impregnated the zone at the lower contact of the porphyry sheet which was wa already altered and porous from the effects of the earlier silver ledge with arsenic mercury and SOU gold of the ores the same geologist observes that they ore are divided into two classes which litch hou boiver ho ever iver were originally anally alike tho the oxidized and the sulphide the former are eble chiefly fly shown in Us the mercur and marlon marion mines and are thus mill far fal the only productive ores ore since the gold cold can be extracted from them by leaching with cyanide ot of pota alum lurn tho the latter tire are beat developed in the golden gadden gate and can be leached beached only alter after 1 the amount ot of gold bold in the ores is 13 never very great rarely exceeding tow or three inches and averaging much less and it Is probable that it exists in the original I 1 nal sulp sulphide hido ores ore as a telluride |