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Show INTER-MOUNTAI- N MINING REVIEW. 5 must have been carried, if his theory is correct) into the veins. This has some Spurrs conclusions are as follows: The color, because the chief minerals in the NUMBER TWO. white porphyry caused the broken lime- veins are volatile at lower temperastone zones by being intruded along the tures than is usual in ores, but it falls BY PROF. MARCUS E. JONES. bedding; it was not the cause of the flat from the absence of tellurium. The Since the publication of my former mineralization, but opened the strata volatilization point of mercury is about article on Mercur the report of the for it; it came up along the bedding 350 degrees Fahrenheit; of arsenic United States Geological Survey by Mr. from an unknown source and may have about 900 degrees; of silver much highSpurr has been published, and it may come from the Eagle Hill mass, which er, and of gold very much higher still. be of interest to review the points of probably was a part of the general in- I do not know of any compound of gold difference between us. truded mass; that at some great depth that is volatile below 1000 degrees FahIt should be known that for some along the bedding, now unknown, there renheit even if that compound were years it has been the custom of the are breaks through which the mineral proved to exist in the veins, while it so Survey to employ young men with no came for the most part, and that its far is not known to exist. That fumes experience to do this kind of work, be- source is also unknown, though he as- of these metals could percolate through cause they will work cheaper than men sumes that the calcite fissures were the loose debris for over a quarter of a mile of experience. This is Mr. Spurrs first channels by which it came, which is a without being deposited, as they are attempt, I am told, at writing up a convenient if not scientific theory; that known to be required to do by this themining camps geology, and it is not to the mineral came up in fumes and not ory, it would be necessary that the be expected that errors will be absent, in solutions. He agrees with me that rocks should be heated above the volanor are they absent. This fact should the Eagle Hill porphyry is not compe- tilizing point of the least volatile metal not, however, detract from the value of tent to cause the mineralization, and in the ore, namely, gold. This would so much of the work as is accurate. so. instead of going to the only ademake the rocks attain at least 1000 deMr. S. F. Emmons, who writes the inquate source, appeals to his imagina- grees of heat, and probably much more troduction to Mr. Spurrs report, is, in tion for a source. than that, but the rocks would melt by my judgment, the best general geoloThe natural and only seemingly rea- the principle of aqueo-igneofusion in 350 this as at about an but economic country, sonable theory of the porphyry sheets gist degrees Fahrenheit, unless geologist his experience is limited, and is that they intruded along the bed- there were an escape for the steam he has conspicuously failed in his the- ding from the Eagle Hill porphyry, generated, and in that case the rocks ory of the mineralization of Leadville, which was thrust up through the sedi- would be calcined, neither of which it having been proved that it is wholly mentary rocks, and forming the moun- facts has actually occurred, but the Incompetent to cause the ore bodies tain at the same time by the elevation rocks, on the contrary, show little or no known to exist there. of the whole as we now find it. In this effects of heat. As to Mercur, the conclusions of case the porphyry sheets will thin out The theory of fumes is, therefore, unMessrs. Spurr and Emmons and my and disappear as you follow the dip tenable, and we must resort to the only own coincide in all respects as to the away from the Eagle Hill nucleus, and other one, that of solutions, as I indigeology, except that they consider the no break will be found along the strike, cated in my previous article. These soporphyry sheets to have been intruded as he and many suppose, and as I once lutions nearly always have sulphur in along the bedding prior to the upheaval thought before I had studied the sub- some form as the active agent, which of the mountains, for which supposi- ject more carefully. The objections to dissolves all the metals, including gold. tion they have no proof, and which is Mr. Spurr' s ideas are that the source There are two schools among scientific In mapping the of the porphyry sheets is only conjec- men as to the nature of these solutions wholly improbable. porphyry outcrops Mr. Spurr departs tured by him; that there is no break of sulphur compounds. One assumes from scientific methods in the extensive along this strike across the dip at the that they are alkaline, and the other use of his imagination. At the time his only place where such a break is proba- that they are acidic. To the miner below the this matters little, as the metals would work was done there was little develop- ble, namely, a point just ment along the porphyry. The surface Hecla shaft, running up and down the be deposited in much the same way in is covered with wash for over nine-tentIn the alkaline method gulch and thence across to the Golden either case. valof the area, so that there is no Gate and beyond; that the greatest the solutions would lose their metals outcrop at all, and it is therefore pure ues are found below this supposed mostly by cooling, and must have been guess work to go into such detail as he break; that there is no other break hot; in the acidic method the solutions does. He has put in porphyry where known from the Hecla to Cedar Fort would lose their metals both by cooling, it does not exist, and he has left out across the mountain along the strike, if they were hot, and by union with porphyry where it does exist. He while the values increase with depth the alkalies of the rocks and depositing makes a thirty-foo- t sheet of porphyry along the dip; that for a distance west the metals as sulphides mainly. The where there is only two feet of it. The of the Eagle Hill porphyry the strata alkaline method requires the presence Sacramento mine he makes almost rise wrhere there is by far the best of large quantities of elewholly of porphyry, while we know it chance for mineralization by fumes, ments, such as silica, in the veins and is almost wholly lime. His theory of but there is practically none compared the deposition of the metals along with the origin of the sheets of porphyry re- with that in the Golden Gate and Mer- and in the silica, which does not occur quires that they should be continuous, cur mines, where the chance for miner- in Mercur proper and only to a very and he therefore runs them in all along alization by fumes is possible only from limited extent at Sunshine. The acidic the stratification without any regard to a so far wholly imaginary source, and theory explains all the facts of cool sowhether they actually occur or not, that the theory of mineralization by lutions and the absence of silica in the while it has been proved that they are solutions and subsequent oxidation is ores. I therefore adhere to this view absent in many places. In the identifi- competent to explain all the facts with- till I can find a better and more satiscation of the black shales as porphyry out resort to the imagination. factory one. he has gone much farther than the The form in which the gold occurs Mr. Spurrs theory of fumes is to my facts warrant. In most places it is im- mind untenable, for it is known that requires a word. It is admitted by all possible to tell certainly whether they fumes are possible only when the min- that sulphuric acid and sulphides of are sedimentary or eruptive, while in erals are heated to a point where they iron and other minerals have the propsome places where he has represented turn into vapor, either they or their erty of dissolving minute quantities of them as eruptive they are fossiliferous. compounds, and that the minerals at gold, but the form in which the gold As to the cause of the mineralization once begin to deposit when their tem- exists in the solutions is a matter of of Mercur, we differ radically. Some perature is lowrer than the vaporizing dispute. There are some persons, with say this is a matter of no consequence, point. The Mercur ores are chiefly only second-han- d information in chembeing only a theory, but, on the contra- those of arsenic mercury, gold and sil- istry, wrho say that there is no such ry! it is a matter of vital importance, ver, with barely a trace of tellurithing as sulphide of gold. If they are for, if his theory is correct, ninety-nin- e um, which latter Mr. Spurr relies upon right such men as Fresenius and the men out of every hundred in Mercur to help him out in his theory of fumes, practical chemists who have been makwight as well hang their harps on the as he assumes that telluride of gold, ing sulphide of gold are fools. (See willows and depart, for the camp can being somewhat volatile, is the form in Fresenius Quantitative Analysis, page never take any rank as a producer, which the gold was carried (in fact 328.) There are others who claim that Geology and flincralization of flercur. while the Golden Gate and Mercur mines have no right to exist at all. 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