Show of lot A some geological facts about the west mounta mountain in mining district written writ ten for uhe ghe re dieto by fred H Per kini E M lei 11 Is lei lei lei lot 1 I lot wa 1 wa capitalists capitalists are asking us on every Q hand why and how we know ore deposits in west mountain district are continuous why we can expect returns from more than surface diggings capital is too shrewd to say because one or two of ginghams Bing hams producers have found ore in depth that such is the case generally speaking of the camp besides the few examples we have let us look into the physical conditions it is a popular idea that all mineral veins have been filled from below by b y material being forced into them while in a molten state this condition of affairs would involve intense heat and the condition of the walls on either side of the ore does not warrant such conditions dit ions while while this explanation is undeniable in the case of ritie and basaltic dikes a multi immense eruptive masses of porphyry and diorite which completely surround the dis brict the high grade arade ores are found in the sedimentary sedi mentry deposits of quartzite and lime and near the south end of the district within this igneous border the porphyry which bounds the district also forms a network of fissures through the paleozoic strata some of which are very large sometimes it intrudes between the different strata in such great quantities that miners are apt to call it a bed of porphyry this intrusion probably took place coincident with the general folding up of the strata 7 W 1 AK A K AW lim icv tude of facts compel us to look for some other explanation for the majority of veins in the west Moun mountain taia district this district is included within an area of twenty miles the main canyons re represent presen i t the folds of the range which have s generally speaking a northeasterly trend the exceptions to this rule are c caused by on the south east and west is the source of the ore while the north boundary is formed by what bingham miners call I 1 granite but which strictly speaking is diorite and does not seem to carry any values which could have been leached beached out and surrendered to the paleozoic strata the porphyry which bounds the district v 15 filling w with i t h molten porphyry the cracks or fissures left open I 1 in n t the h e southern portion of the district the largest amount of in i n e r a libation liza tion has gone on also in this portion of the t h e district are the largest and most continuous ore chutes the contact veins vary in thickness but all seem to have su surrendered r themselves to the ravaging effects of the strong alkali waters and vapors and the cavities thus formed were filled with the precious metals the larger of these contact or bed veins have an east and west dip varies greatly it seems to be the rule to st with depth we are asked many times why veins just as large and as favorably situated carry little or no value while others are so very rich all veins of whatever kind whether bearing bearint 0 valuable minerals mine rala or not are the result te qt of modem movements ants in tb the e upper portion of the earths crust producing cracks or crevices which have been subsequently enlarged and filled with some material different in its physical and chemical qualities and appearance from the rocks in which the fracture has taken place f these fissures may be the result of e earthquakes or the readjustment of the pressure caused by the thinning of one portion of the crust by denudation and the thickening of another portion by deposition upon it of all the material brought down from the mountains by actions of rivers or more likely by the process of mountain building now it does not follow that all these f fissures IS will produce mineral veins for there must be a combination of circumstances to cause such deposition very frequently these lines of faults become the bed of a water course and in time a gulch or canyon since the popular idea of molten filling except in the case of igneous rocks is not sound we must look for another cause it is evident that water is the active factor in all these changes we must remember that a considerable portion of the water which falls upon the surface of the earth does not pa pass s 9 off promptly into the rivers but is absorbed by the earth and rocks and by the action of gravity penetrates depths practically unknown while this thid water at the surface may be cold we know that before it goes very far down it gets hot now we are able to understand the action of bf thew the waters aters we have cold water descending and heated waters tending to rise or oi eing being bl forced to the surface along the lines of least resistance such as the fault fissures by pressure of steam the ability of the waters to decompose rocks depends on oaf the presence of carbonic acid and alkaline materials such as carbonate of soda and potash and afi atie e solvent powers are increased with the raise of temperature the first carbonic gas in rai eatn 1 n water is derived irom from the atmosphere and the moment it touches the earth it begins its work of decomposition picking r up one mineral and de positing another water thus traversing cg an open fissure even though it be in hard quartzite would leave a portion of its contents on the walls both sides alike now if these percolating waters reach a limestone there is where it does the most moat work it eats out passages and chambers and as particles of lime are dissolved it deposits mineral such deposits are irregularly shaped due to the vagaries of the water which hollow out the chambers and passages the source of the mineral thus deposited is to be found in the country rocks of the regi region mainly the eruptive the porphyry is near at hand and even though it is low grade the water of ages circulating through it concentrates it for the use of mankind A moments thought 11 will show us that under any circumstances some such results as have been outlined have caused the mineral to be deposited even had the original veins 1 been solid masses of gold silye silver r lead 0 or copper their contents would as they were worn away have been scattered tar far and wide through the rocks which were formed out of the earths first crust of course the nearer the source of wealth the greater grea ter are the values so far as aa the writer knows no rich strike in the igneous rocks has been encountered but all the porphyry carries values we can now see why all fractured regions are not now if both the source of ore and the favorable conditions for are lacking no one would look for returns from such a country but the west mountain district has both highly developed and especially so 86 in the southern portion of the camp lime beds ranging from two to twenty ave five feet in thickness are num numerous erous and are crossed and re crossed by large fissures in many of which klippl slipping i ng and grinding has gone on so that thai the walls wall sare are crushed and brok broken for mauv many feet athu thus allowing good I 1 circulation of waters and large areas for deposition another way in which this broken broke up area ans aids us in making makina safe investment in 06 camp is that much of the country is expose for us usand and allows us to prospect with le tunneling but as it is broken the ore oren frequently lost by cut off fissures but ww with a little study of the ex exposed portions of tho ti strata it is readily located the regularity of the faults in course and distance MOO make mining simple as compared with much of w 01 mineralized world too much praise cannot be given to the large companies and smaller ones too I 1 lot i the milligent dill igent manner in which mining is no now being carried on in th the W mountain mining district |