Show I 1 WHAT VEINS TO CHOOSE j ARTHUR LAKES IN MINES AND MINERALS X 5 ic J aw on en entering enteria terin a new and untried region of crystalline rocks such as one of granites goranites gra and gneiss es accompanied by dikes or eruptive rocks such as porphyries ries dio rites etc it is very likely that the prospector will be at once struck by the appearance of big wide quartz veins cutting across the country their outcrops indicated by plainly seen masses of white bull quartz standing up here and there prominently above the hill sides and on the hill tops ani easily traceable for a long distance measured perhaps by miles rather than feet these are the mammoth or so called mother veins of the district and are good signs for that district in so far as they show that the region has been fissured and veined if he be a tenderfoot prospector he will be specially impressed by the appearance of these great big veins and may promptly locate as many of them as possible A more experienced prospector or mining man whilst he will certainly pay some of these mammoth veins of fine looking bull quartz his attention yet from experience he will be apt to distrust them and look about in the vicinity for some smaller and less showy veins it is to be remembered that all quartz veins showing on the surface are by no means mineralized or so scantily so as not to be worth exploiting for example going up clear creek canyon to idaho springs georgetown or central city in colorado we pass hundreds of big quartz veins and pegmatite veins not one of which shows any surface sign of being mineralized and even when we reach central city or some other of the mining camps amongst the numerous big veins observed outcropping cropping out en n the surface not one in ten is there that is mineralized er or that has a mine on it or even a prospect hole in the general fissuring of a region it may be hard to explain or surmise why some fissures were filled with barren quartz and others with mineralized quartz yet it is so of the barren fissures opened and filled by quartz matter those in direct contact with a porphyry dike or eruptive rock are on geological grounds the most likely to be mineralized by metallic minerals but this is no absolute rule pure white veins of bull quartz may appear at close contact of a porphyry dike and yet show no surface in dhea di cation tion of being mineralized again some veins with no contact porphyry on either side or near them may show much better mineral signs than those seemingly more favorably geologically situated the big quartz veins that I 1 have mentioned which may be 20 to 50 feet wide passing through the country like great cy clodean cl walls or like ancient roads may represent the principal lines of the fissuring or fracturing of the country that produced near them many smaller minor or secondary fractures filled with quartz or mineral the latter are commonly found the best mineralized and the most available for mining manint purposes sometimes these mother veins are almost absolutely pure bull quartz or else quartz and feldspar fel spar called pe pegmatite ma tite without a trace of others show a little mineral here and there but so diffused and scattered that it would not pay to work whilst in the narrower veins the is apt to be much more concentrated besides these smaller veins are much easier to develop from a mining point of view among the first things in a region traversed by fissure veins as yet enod unopened or at most by only a ten foot prospect hole is the question which of these are mineralized and which will likely prove sufficiently mineralized erali zed in depth to make a mine the prospector may have many veins in such a region to choose from and he wishes to know on which he shall locate on which he h had better concentrate his work A big vein of pure white or bull quartz is apt at depth to prove or at I 1 best u unproductive and on general ples pies had better be avoided another big quartz vein however may be somewhat copiously stained with iron oxide and present an attractive appearance such an iron staining is not to be wholly relied upon it may be questionable whether such iron staining was derived from the oxidation of iron bearing minerals in the vein such as iron pyrites or copper pyrites or whether the stain might not have been indirectly derived from some other source such as some contiguous rock highly charged with such iron bearing silicates as hornblende or mica in addition to the iron staining we would look for some more positive signs of internal such as a honeycombed appearance pe arance of the rusty quartz indicating the former presence of cubes of iron pyrites which dropping out by oxidization have produced the well known surface blossom or gossan of miners if there is plenty of this gossan or blossom and further if it should be stained greenish by copper carbonate the inference is that the vein is mineralized by either iron or copper pyrites or both though to what extent we may not be able to prove if the gossan is abundant it would argue for a more abundant in depth than if it it were meager though this cannot always be relied on As a further proof of internal mine mineral rall bation we might look among th the e gossan for traces of free gold A honeycombed oxidized condition of the quartz is a good sign in a surface outcrop signs too of a general decomposition of the quartz or of an adjacent country rock are much more promising than when the vein as well as the adjacent country are hard pure and commonly the more rotten a vein as well as the adjacent country is the better the promise geodes ceodes or little cavities running through the quartz lined with quartz crystals are better than hard solid massive quartz A banded ribbon structure or appearance pe arance of the vein vein is in many cases more favorable than a homogeneous appearance having decided to make a trial of a vein by a preliminary opening it is desirable to get as much depth as possible below the outcrop so as to crosscut the vein and show up its probable contents when this is accomplished complis hed and the vein is well crosscut from wall to wall the next thing to lo consider is the character of the metallic minerals found in it and what they prognosticate as aa to the state of the vein in depth and its pro probable baVle future condition if in crosscutting the quartz vein it is found to contain only a few scattered crystals of iron pyrite this is no absolute proof of its being well mineralized at depth with gold bearing pyrites because pyrite is common to many non ore bearing rocks e g g coal if the pyrite however is well diffused or abundant it is a good sign copper pyrite is almost a sure sign of future mineral iza tion because copper pyrite is not found in other than ore bearing rocks iron or copper pyrite would argue for the vein being in depth a gold bearing one if crystals of galena or zinc blende are found these show cerLa certainly that the vein has been truly mineralized by true ore solutions galena would argue in favor of a lead silver vein at depth and zinc zine blende might suggest either gold old or silver or both combined or copper below the next consideration is as to the prevailing location or disposition of the ore in the vein it may be generally diffused but more commonly in the case of large quartz fissure veins the ore zone will be found close or near to the hanging or foot wall preferably the latter whilst the heart of the vein veil is liable to be barren or nearly barren bull quartz these are notable exceptions to the of these big veins some soine like the alaska treadwell vein have been found more or less profitably mineralized right across their entire width these are usually large low grade propositions even in these pay streaks of richer or more concentrated cent rated bodies of ore may occur along particular zones especially close to one or other of the walls we have that the crosscut in the above cases have been made sufficiently low down in the vein as to and to be below surface oxidizing agencies show the true condition of the vein the greater the variety of minerals in a vein such as iron and copper pyrite galena and zinc zine blende the greater the probability of its keeping down in a good mineralized condition with depth in some out cropping quartz v veins eins the oxidizing influences go 90 down so deep that it is not possible to open a crosscut prospecting hole sufficiently low down to show the condition of the vein so far down as these oxidizing influences influence s extend in a gold vein so far is the probabilities after the ore free milling this are of its turning into a concentrating or smelting smelling sm elting proposition or into one containing both massive ore for smelting smelling sm elting and a proportion of dis disseminated abed ore tor for concentration tra tion As regards erecting a mill no mill should be erected on the premises until there is sufficient ore on the dump or reasonably developed in the mine to keep that mill active for some months if there is some doubt as to whether the ore should be treated by a cyanide or some other process it is advisable for the prospector to send a consignment of or pounds or more to a sampling works such as woods co denver and taylor brunton sampling works company salt lake who make a business of determining the proper processes to be applied to different ore bodies tn in a young unopened district lavish expenditure is to be avoided such as might be warranted in the case of a fully developed mine it Is a case of creeping before walking and there should be no such talk as that of ordering air drills to open up the country on a big scale by long crosscuts cross cuts tunnels and the like until those veins have been absolu absolutely bitely proven by the simple use of pick ind and shovel hand drills and powder when there are a good many promising looking vens veins to choose from whilst it may be all right to make locations and secure those veins it is advisable to concentrate work and energy on one and that the most promising and most easily developed when this has been well proven up and its value e assured it will speak much for the possibilities of the other veins and there will be much greater eh chance ance of enlisting capital to come in and take up the other properties |