Show aliel oli elIN IN lei I 1 a lei im lei to lei im lei lel lei IN lei 14 14 14 IM I M lei lei 14 if lei lei iola im IN im lei 14 lin lei 11 i THE GEOLOGY OF TONOPAH NEVADA i from report q of f T 7 1 4 I knapp the geological conditions in the tono tone pah nevada and surrounding districts is to many an unknown quantity A number of mining engineers have written their opinions in a brief way but the subject has never been treated exhaustively hau from a scientific standpoint the wonderful discoveries of ore and the consequent rapid development of the district during the two years just passed has caused such widespread interest in ih that section that the united states government has ordered a geological survey of the tonopah district and will most likely extend it to include gold mountain and han dapah which districts are also cutting quite a figure in the mining operations of the sage brush state the report of the government ern ment engineers will be awaited with the keenest interest and the publication will be in great demand when it issues from the press early in the history of tonopah To S A knapp kaapp M E at present general manager of the ohio tonopah mine made a study of the geological features of the now famous camp he made a report to his associates his views of conditions expressed at that time have been fully substantiated by subsequent developments mr knapp has offered his report without amendment for in this number of the mining review it is as follows the first discovery and location was upon a series of parallel ledges which out cropped the surface four in number subsequent developments within the same area showed fourteen ledges all parallel and doubtless miny many others will be shown when systematic crosscutting cross cutting commences these claims eight in number alethe are the property of the tonopah company of noi nei vada largely composed of philadelphia people and are being vigorously exploited three deep s shafts haats having been planned and two started later later three parallel claims showing similar formation and parallel ledges to the first group were located by others and now constitute what is known as the gold hill property taken together these properties show a a series of about twenty known parallel ledges which stralie slightly north of east and south of west and a slight dip to the north in a width of about feet the length 1 bength of the outcrop exposed along the course of the ledges varying from feet at t the south end of this foot strip to 0 1200 feet in length at the north end on the east and west the ledges with their enclosing formation are covered by a series of surface porphyry flows and it is only by sinking through this capping that the ledges and ore are uncovered the format formation ln covering this series of ledges is a light porphyry and where exposed on the surface or underground is practically the same in character all carrying some value ranging from 2 ounces silver and trace of gold upwards the ledges are strong ranging from one foot to twenty feet in width have good food walls and bear every evidence of being true fissure 1 veins eins they are faulted but little and then with but a slight throw they are mineralized throughout their extent so far as developed ve loped with secondary enrichments enrich ments as a rule accompanying the faults the ledges and enclosing porphyry are very similar to the format formation ionin in butte montana and the consensus of opinion of engineers and practical miners familiar with both groups is that the ledges can be de upon to hold their size and value to great depths as they habein have in butte in butte the surface ores were oxidized oreland ores ore sand and silver with small amounts of copper below the water level copper sulphides sulp hides carrying silver and small amount of gold came in at tonopah the principal ore being silver sulphides sulp hides and gold the character is not likely to change when water level is reached the principal ore is a hard compact close grained quartz carrying silver sulphide and gold intimately associated associate ed with the quartz with no base present except a small amount of iron and some manganese oxide at certain points and is undoubtedly a primary ore practically unaltered since its original deposition it much resembles the ore from deep levels of the comstock the secondary ores which occur in in conjunction with the faults are principally chlorides with some gold in the principal ores gold is present in the proportion of 25 gold to each ounces silver and thus far the average of all the ores ledges opened and exposed is about ounces silver and 35 gold per ton the ledges being continuous ore bodies with practically no barren material within the walls in sinking to the present level the ledges have improved in size and value and at the bottom of the present work show wide ledges and in many places enormously rich ores the bottom of the most western opening mizpah ledge on the buckboard claim shows a ledge eight feet wide of df ore and back of this eleven feet in width of ore during november and december 1901 fifteen hundred tons were hoisted from this lease one hundred feet in length with a small gasoline hoist this ore being valued at per ton in every opening of importance upon all this system of ledges improvement in size and value of the ledger ledge has been noted the distance to which these ledges extend both east and west from the outcrop ping uncovered portion is probably very considerable this being evidenced by the large number of fissures some twenty now known their parallelism similarity of 0 dip and a nd strike and regularity showing that the movement which caused this fissuring was wag general to a large area the surface showing shoving that a width of dt at least five thousand feet was thus affected and such being the case the fissures would extend both east and west a very consider considerable abie distance the vein building solutions which brought in the quartz and mineral would circulate throughout their extent and the deposition would be similar simi larin in character and amount to 0 that where ledges are now known additional dit ional evidence of this andoe and of 6 a common source of the solutions Is given by the similarity of the true sulphide ores in all portions of the district and the maintain ance of the same relative proportions of goad and silver liver hence it is reasonable to suppose that wherever this same Byg tem of fissures is found we shall find the same character of ledges and ore |