Show THE GREAT BLANKET ORE DEPOSIT OF special correspondence quite a little discussion has gone on among miners and prospectors regarding he nature of the thunder mountain ore deposits the boom literature of the newspapers have it a volcanic condition similar to cripple creek and all shades of opinion on are expressed pro and con about it in camp the truth of it is that the volcanic rock so prevalent about the mines have disguised the real nature of the deposits to even very acute and competent mining men having had three months time to study the surrounding conditions and examine into the mature of the ores and the mode of occurrence at many different points I 1 believe there should be no longer any disagreement regarding the matter and conditions prevalent and with this make a statement of the facts in the case which the exploitation of the mines up to the present time have proven As a new arrival about the first thing you are told about and shown are the great pieces of charcoal and petrified wood that are found right in the ore I 1 have seen many feet under solid strata eighteen inches of charcoal that will burn in an open opan fire and run five dollars per ton in gold now the most of the ores are of a dark earthy and talcose material mottled and mixed with sand and gravel and wash worn boulders as large as a cocoanut coco anut the dark coloring is derived from the presence of carbonaceous material of a nature containing many leaf impressions the floor of the deposit is diorite the hanging wall is rhyolite which resembles quartzite in appearance there are two hundred and fifty feet of alternating layers of dark and light colored capped with coarse wash worn conglomerate and soft carbonaceous that overlie over lie the and the ore the ore deposits lie in almost horizontal position these sediments have been much altered and buried in most places first by a flow of material or geyser mud and lastly by a basalt capping burying them from sight in many places what are now the ore deposits was a marginal sea or lake deposit of tertiary age and was primarily a placer bed but the out flowing of over these sediments forming the immediate cover of the ore deposits has brought about a secondary enrichment of the bed thermal waters were apparently the vehicle that transported the gold which was one of the constituent metals of the magma downward and laterally through the sediments until brought to the impervious diorite floor flook making the detri tal accumulation a zone by itself above a zone of saturation the gold evidently carried in a solution of iron sulphate was precipitated as sulphide by the organic material present the deposit then is a blanket but it has not an exact horizontal position the reason being that the itie district has been subjected to recent changes which have tilted the sediments into undulating folds the backs of the an ti clines were more easily eroded and have been removed the lines having been more or less compressed and capped by subsequent igneous matter have withstood the ceaseless action of times denudating denu dating agents and remain in patches capping the high hills there are three of these patches in the district one on thunder mountain with an areal extent of about five square miles it is in the form of an irregular clipse about five miles in length and from one half to two miles in width the next in import ance is four miles east of thunder mountain on lookout peak and covers many more square miles another patch is on rainbow peak five miles west of thunder mountain the area of which has not been determined there may be a forth development of these formations on the divide between monumental and rush creeks ten to fifteen miles north of the dewey mine there is in all probably fifteen or twenty square miles of mining ground on this fossilized sili zed lava capped secondarily enriched placer in the district should it prove with further development to be as rich as the famous dewey mine has it will supply an enormous tonnage for many years to come this form of ore deposit is not a singular or unheard of occurrence it has not upset the philosophy of the mine mine expert or brought out a new thing in fact these pre placers were the firsht mines discovered in the state of idaho forty two years ago and in this county florence and warren both are similar occurrences but were worked out as placers it is certain that the gold of these camps was deposited on what is now the high hills before the canyons of the salmon river a gorge that is five thousand feet deep had begun to wear down and what appears to be isolated patches now are remnants left here and there of a gold placer that at one time covered an area of thirteen hundred square miles in the interior of idaho even now are many different places dotted over a territory one hundred and fifty miles long east and west by seventy five miles wide north and south that manifest sir similar pilar condit conditions ions pre sent at thunder mountain and it is boroi than likely that a part of this at least is the richest field in the west S SF F HUNT roosevelt idaho |