248 KEMP'S ORE DEPOSITS. 



have been referred to the ocean, to ocean currents, and to glaciers ; 

 but it is now well established that they are river gravels, formed 

 when the rainfall was probably in excess of what it is to-day, and 

 when the attitude of the land toward the ocean may have been 

 different. 1 



2.12.13. Example 45. Gold Quartz Veins. Veins of gold- 

 bearing quartz, usually described as segregated veins, in slates 

 and other metamorphic rocks, and more or less parallel with the 

 bedding. The quartz contains auriferous pyrite, free gold, 

 arsenopyrite, chalcopyrite, tetrahedrite, galena, and blende, but 

 pyrites is far the most abundant. Some tellurides have been 

 noted by Silliman at Carson Hill, Calaveras County. The veins 

 approximate at times a lenticular shape, which is less marked in 

 California than in some other regions, and which shows analogies 

 of shape with pyrites lenses (Example 16) and magnetite lenses 

 (Example 12). In such cases the fissure-vein character is some- 



1 G. F. Becker, " Notes on the Stratigraphy of California," Bull 19, 

 U S. GeoL Survey. " Structure of the Sierra Nevadas," G. S. A., II. 43. 

 W. P. Blake, " The Various Forms in which Gold Occurs," Re}). Director 

 of the Mint, 1884, p. 573. A. J. Bowie, Jr., "Hydraulic Mining in Cali- 

 fornia," M. E., VI. 27. R. E. Browne, " The Ancient River Beds of the 

 Forest Hill Divide," Rep. Col. State Mineralogist, 1890, p. 435. RPC. T. 

 Egleston, "Formation of Gold Nuggets and Placer Deposits," M. E., IX. 

 63. "Working Placer Deposits in the United States," School of 3fiu.es 

 Quarterly, VII., p. 101. J. H. Hammond, "Auriferous Gravels of Cali- 

 fornia," Rep. Director of the Mint, 1881, p. 616. Rec. Rep. Cal. State 

 Mineralogist, 1889, p. 105. H. G. Hanks, "Placer Gold," Rep. Director 

 of the Mint, 1882, p. 728. H. G. Hanks and William Irelan, Rep. Cal. State 

 Mineralogist, Annual. T. S. Hunt, "On a Recent Formation of Quartz, 

 and on Silicification in California," Engineering and Mining Journal, May 

 29, 1880, 369. J. Leconte, "The Old River Beds of California," Amer. 

 Jour. Sci., iii., XIX. 80, p. 176. J. J. McGillivray, "The Old River Beds 

 of the Sierra Nevada of California," Rep. Director of the Mint, 1 C 81, p. 

 630. R. I. Murchison, " Siluria," etc. Contains a sketch of the distribu- 

 tion of gold over the earth. J. S. Newberry, " On the Genesis and Distri- 

 bution of Gold," School of Mines Quarterly, Vol. III.; Engineering and 

 Mining Journal, Dec. 24 and 3^ 1881. J. A. Phillips, " Notes on the 

 Chemical Geology of the California Gold Fields," Philos. Mag., Vol. 

 XXXVI., p. 3^1 ; Proc. Roy. Soc., XVI. 294 ; Amer. Jour. Sci., ii., XL VII. 

 134. B. S lliman, "On the Deep Placers of the South and Middle Yuba, 

 Nevada County, California," Amer. Jour. Sci., ii., XL. 1. J. D. Whitney, 

 "Auriferous Gravels of the Sierras/' Cambridge, 1880. "Climatic Changes 

 in Later Geological Times," Cambridge. 



