LEAD AND SILVER. 185 



also penetrated the adjoining rocks through cross joints and cleav- 

 age cracks. 



These additional points are also advanced: 



I. That the solutions came from above. 



II. That they were derived mainly from the neighboring 

 eruptive rocks. 



2.08.08. The first four points are doubtless correct, and No. 

 III. is an important application of the theory of replacement, fre- 

 quently referred to in the introduction. The last two propositions 

 merit less confidence. Seven additional years of mining have 

 brought many new facts to light and have led others (A. A. Blow 

 in particular, whose valuable paper is cited below) to refer the 

 ores to upward rising currents. Emmons foresaw this possibility 

 and mentioned it on p. 584 of his monograph. The amount of the 

 adjacent, igneous rocks is quite insufficient to afford the ore. In 

 alteration the galena has passed through an intermediate stage of 

 sulphate before changing to carbonate. These mines have been 

 important not alone in their own metallic products, but in fur- 

 nishing the smelters with oxidized lead ores they have sup- 

 plied a means of reduction for many other more refractory ones, 

 which could be conveniently beneficiated through the medium of 

 lead. 1 



2.08.09. Example 30a. Ten Mile, Summit County. Bodies 



1 F. M. Amelung, "The Geology of the Leadville Ore District," Engi- 

 neering and Mining Journal, April 16, 1880, p. 25. " On the Origin of the 

 Ore," Ibid., Dec. 20, 1879. A. A. Blow, "The Geology and Ore Deposits 

 of Iron Hill, Leadville, Colo.," M. E., June, 1889. Rec. Ann. Rep. Colo. 

 School of Minea, 1887, p. 62. S. F. Emmons, "Geology and Mining Indus- 

 try of Leadville," Monograph 12, U. S. Geol. Survey. Rec. Second Ann. 

 Rep. Director of U. S. Geol. Survey. Rec. Tenth Census, Vol. XIII., p. 

 76. F. T. Freeland, " The Sulphide Deposits of South Iron Hill, Lead- 

 ville," M. E., XIV. 181. C. Henric h, " The Character of the Leadville Ore 

 Deposits," Engineering and Mining Journal, Dec. 27, 1879, p. 470. "Ori- 

 gin of the Leadville Deposits," Engineering and Mining Journal, M..y 

 12, 1888, p. 33. "On the Evening Star Mine," Ibid., May 7, 1881, p. 361. 

 "Leadville Geology," Ibid., June 3 and 10, 1882 ; Historical, May 30, April 

 6, 13, 20, 27, 1878 ; also many other allusions, 1879-81. R. W. Raymond, 

 Rep. on the Little Pittsburg Mine, Engineering and Mining Journal, June 

 28, 1879. L. D. Ricketts, The Ores of Leadville, Princeton, 1883. C. M. 

 Rolker, " Notes on Leadville Ore Deposits," M. E., XIV. 273, 949. F. L. 

 Vinton, " Leadville and the Iron Mine," Engineering and Mining Journal, 

 Feb. 15, 1879, p. 110 ; also June 28, p. 465. 



