Salt Lake Mining Review | 1905-02-15 | Page 5 | Primmer Lessons in the Origin of Veins

primmer lessons in the origin of veins written for the mining minin i g review LL not to the mining expert nor to professors of 0 geology are these lines respectfully dedicated but to laymen who may be interested and especially to those prospectors whose information on the origin of veins may have been gathered solely from the hard school of experience in the hills because of years pleasant association with hundreds of prospectors J F gimis and knowing bowing their intelligence telli gence the important part they enact as the vanguard of mining their weaknesses and too often vagaries the writer of this should be pardoned for a little plain talk the hardheaded hard headed prospector and the average so called mining expert in their spheres of thought activity and mutual deep seated prejudices are as widely separated as are the poles the prospectors prejudiced analysis of a mining expert would be nearly as follows foi ios yellow boots 20 per cent corduroy suit 30 per cent swagger 30 per cent and book larnin 20 per cent and in many instances the lowly prospector could truthfully substitute gall for book larnin and then be close to the truth the average mining expert looks down with lofty contempt on the rough clad grizzled prospector and his lifelong life long practical communion with formations and float the mental vision of the prospector is too often clouded by lack of information of those simple and easily learned laws of vein forming which if only mastered and duly heeded would save no end of hard labor and keen disappointment at the paucity of returns from a veritable wildcat the true mining expert is as widely separated from the strutting counterfeit as is a 20 gold piece from a leaden plunk those who have had the pleasure of being in the field with professor arthur lakes of colorado never weary of telling of his genial democratic way and his willingness to impart information to those less fortunate some twenty five years ago many of us had the pleasure of meeting prof newbury late state geologist of new york that portion of utah known as the marys vale country so charming in its scenic beauty and grandeur and fascinating geology was often honored with his presence prof newbury was apparently never more delighted never more at his ease than when jointly occupying some solitary cabin in the heart of the grand old baldy baidy range ana eating salt side and B P bread and spinning s pin yarns with the rough but all wool prospector those eminent geologists at the top of their prof professions sessions es are mentioned because they are types of the real mining expert to whom the physical features of thet the earth are as an open book the average prospector is too apt to dictate to nature and to assign impossible causes for the various phenomena that daily confront him the average mining expert if college bred is too academic clings too closely to the scientific laws odthe of the medes and persians and unless mentally broad and elastic will continue in the mhd academic groove or rut passing over the causes of earth frac tures called fissures and divesting the subject of unnecessary details we will plunge into the subject and if possible stay there As a rule fissures were formed in eruptive rocks which came to the surface in the condition of magma or hot pasty mud it is also a well known fact that the earths heat increases at about one degree for each sixty feet in depth in volcanic or eruptive areas the ratio of increase is often much greater as is exemplified in the deep workings on the comstock lode where the water is so hot that the miners turn at the face is limited to a few minutes of course the heat was tremendously intensified at the time time when the fissures were being filled and as far as the enormous pressure in the deep regions would permit the water fiod ta CROSS SECTION OF CROSS SECTION OF GASH VEIN CONTACT VEIN was in the condition of super heated steam ol 01 vapor all eruptive rocks contain alkaline and other acids in a greater or lesser degree water circulating through such an environment would become highly acidulous and capable of dissolving and appropriating pria ting atoms of metal that might be present in the rocks and atoms of quartz feldspar etc even moderately warm or cold water often dissolves calcareous atoms brings them to the surface and builds mounds as at soda springs or as heated water builds geyser cones etc in the last number of the mining review the writer referred to an instance in millard county utah where warm water is busily engaged in bringing up atoms of iron and depositing them as an iron sheet or stratum at the surface and it was wag in compliance with the method before indicated that all fissures and contacts were filled and all deposits of the precious metals were formed by the circulation of powerful solvents called solutions lut ions and the prospector will readily understand that the foregoing modus operandi operand is much more natural and easy to comprehend than the pushed up theory so often advanced in order to explain the origin of veins in fact the hot solution course accounts for all of the various phenomena present in the problem while the pushed up explanation clumsily and unnaturally accounts for but one the average prospectors pardon is humbly in invoked voRea and his patience e earnestly craved while one of his pet and nd most comforting for ting heresies her esies is ruthlessly attacked he is not without some dubiety asked to take a square look at fig 1 herewith and which is intended to represent a vein you may call the artist who draw dr awed ed it a blank if you care to and you may sneer at the cold dreary truth the drawing rudely but forcibly illustrates but its the truth just the same perhaps you dont like the picture because the lesson it teaches is too f familiar how often during your hard but fascinating pursuit have you sunk an incline at a fig 1 and crosscut cross cut to the hanger and how often have you said the ore is all right and it rain down it must therefore have a come up tiie the narrowing down of the ore boy body is just a pinch the average prospector detests even the thought of twisting a windlass and he goes down the hill and runs a tunnel and in nine cases out of f ten on with results as indicated in fig 1 but the prospector may take comfort in the knowledge that his mortal enemy the corduroyed and yellow legged mining expert had his co tinsel counsel been asked would have advised running the tunnel in southern utah there have been three tunnels driven practically illy towards the same point in the ridge at a cost of fully where one tunnel would have determined the question of ore or a shaft costing would have answered even better and the man who engineered the unsuccessful job poses as a mining expert among down east tenderfeet tender feet and slings geological jargon and mining nomenclature with about the same facility if the pushed up theory of vein origin 0 were correct the condition s as indicated in fig 1 would be impossible but it is the old and familiar gash vein that like a golden swamp light has too often lured the prospector on and on until the shadows from over the great divide warned him that tho the toll toil and privations of 6 a lifetime life time alme were without compensation the genesis of a gash vein is as follows the hot pasty magma or otherwise on emerging from its deep seated source overflowed over flowed and occupied contiguous depressions in cooling and shrinking season cracks were formed and the surface badly shattered by more rapid cooling such conditions were afterwards favorable to the circulation of thermal solutions which from deep and shallow crevices and from the sides of the season crack or superficial fissure dissolved the atoms of metal silica feldspar etc and carried them to the shrinkage crack called a fissure in due course of time a full grown gash vein was formed and then practically awaited the affectionate attention of some unwary prospector hect or dame nature with her glaciers has ploughed sloughed hed out and destroyed thousands of those deadly imitations but in some instances failed to conceal the remains from keen eyed prospectors who have spent fe y V 7 ili az CROSS SECTION or OF FISSURE VE VEINS INS months seeking the ledge from which the float had been torn away down south in N nevada evada a man with more than ordinary intelligence and money is hopefully developing a twelve inch vein of red clay the remains of a big blowout blow out of gold bearing quartz that crops on the hillside not fifty feet above the face of his tunnel fig 2 represents a contact vein with quartzite foot wall and lime hanger also in nevada it will be observed that the upper portion of the quartzite is badly shattered it is not a remarkable fact that a certain distance down on the dip of the vein or as far down as tho the shattered condition of the quartzite extends the vein carries an average of about 12 gold per ton and and a little silver nor is it r remarkable that below the shattered condition of the foot wall on down to the bottom of the incline shaft the values steadily decrease to two or three dollars per ton at the bottom the lime hanging wall in the cho lower portion of the mine is somewhat shattered but the gold content has ha s largely decreased lime is a notorious carrier of I 1 lead ead and generally lean in gold while reverse conditions obtain in quartzite ozite thus the teachings are that the solutions entered the contact through the shattered foot wall and deposited the gold and it is just another instance added to the gash vein where the values neither rained down nor came up from the deep another instance of a vein having been filled from the sides is found in fig 3 and which represents a fissure there is no doubt about the vein represented by fig 3 going down in the bottom of the by which the vein is partially opened is a foot or more of lime spar and the filling carries about 12 per cent of lead the country rock is birdseye porphyry and the spar and lead certainly came from limestone situated at great depth where either of 0 f the walls is shattered there is found rich ore between the shattered points the filling is lean there is little or no lead in the upper portion of the vein such conditions are suggestive and unequivocal fig 4 represents a fissure which was filled from the lower portions of the opening and the only difference between it and fig 3 is the matter of depth where the solutions lut ions following lines of least resistance entered the fissure the richness of a vein depends dep ends on the presence of three principal pal conditions to wit first the quantity of the metallic atoms in country rock through which the s solutions circulated second the strength and temperature ot at the solutions all other conditions being equal hot solutions would have possessed posses sea greater solvent properties than cooler solutions third the rapidity of cf movement of the solutions and for the following reasons metallic atoms are more easily dissolved and appropriated or held in suspension by solutions than are atoms of silica thus all other conditions being equal a rapidly moving solution passing through a given distance would extract and appropriate a relatively greater quantity of the metals than of silica and would reach the limit of its appropriative capacity with a greater relative quantity of metal than of silica and a slowly circulating solution would reach the limit of its appropriative capacity charged with a relatively greater quantity of silica than of the metals such are the simple operations of nature when industriously gathering the wide 1 ly ay separated atoms of gold and silver and depositing them in veins and other places within the reach of mankind whose civilize 1 i 1 tion and progress have been greatly aided r by the use of the precious metals the acceptance of the foregoing simple truths means the ability to solve countless problems that otherwise would be inex J F GIBBS