CONCLUSIONS. 449 



The water issuiii,^- from Steamboat undoubtodly comes from the Sierra 

 Nevada, and this is also the probable origin of the water of the Coinstock- 

 lode. In each case the water descends to great depths before rising to its 

 point of issne. Now, if the ores of both localities came from infragran- 

 itic sources, these sources must be very near together, but of very differ- 

 ent characters. Foi- tliis difference it is not easy to account. But if only 

 the solvents came from below the granite and the metals from the i-ocks 

 comparatively near the surface, it is easy to see why the two deposits differ 

 as they do. 



Heavy metals in granite Wlule lu the granite investigated for this memoir 



only arsenic, antimony, copper, and lead have been found, lead is almost or 

 quite always argentiferous and silver is rarely, if ever, free from gold. Silver 

 has been detected by Professor Sandberger in the mica of German granites 

 and Mr. Siniundi has found gold in the granites of Idaho. Gold is always 

 accompanied by silver. Zinc also has been found in gneiss-micas. Arsenic, 

 antimony, lead, and copper are so frequently associated in nature with gold, 

 silver, and zinc as to lead to the supposition that they often have a common 

 source. Mercur}' is not yet known as a conq)onent of granite or gneiss, but 

 all the metals associated with it have been detected in these rocks. The 

 probability that the quicksilver alone is derived from an infragranitic source 

 is exceedingly small and is not supported by a single known fact. 



Conclusions, — Tliu evidcncc is overwhelmingly in t\u or of the supposition 

 that the cinnabar, pyrite, and gold of the quicksilver mines of the Pacific 

 slope reached their present positions in hot solutions of double sulphides, 



iul volatilizers kuown, ami form volatile combiuations with almost every substance. Besides silicon, 

 the metals have a great affinity with them. All those which occur in the Comstock vein could ascend 

 in a g.aseous state in combination with one or other of them. They must then be precipitated in the 

 upper parts as metallic oxides or chlorides, and in the native state. Thus the fissure was gradually 

 filled, from its upper portion downwards, with all the elements which we find chemically deposited in 

 it." In my report, page 286, 1 wrote : " Floods of heated waters now rose from a depth of two or more 

 miles certainly carrying carbonic and suli)hydric acids', and possibly other active reagents, in solution. 

 The water followed the course of the main fissure as closely as circumstances permitted, but was de- 

 flected to a great extent into the fractured mass of the east country, where decomposition resulted. 

 Silica and metallic salts were set free from the mineral constituents of the rock, and were carried into 

 the cuinparatively open spaces near the main fissure, where they were redeposited" (see, also, ibid., pp. 

 2-26. 283, 380, 3"J0). Professor Newberry attributes to von Kichthofon and himself approves the very 

 theory which I was at great pains to support. The hypothesis which von Richthofen advocates New- 

 berry seems entirely to have overlooked (sec, also, The genesis of certain ore deposits, by S. F. Emmons : 

 Trans. Am. Inst. Min. Eng., vol. \->, 1887, p. 125). 

 JION SIII 29 



