LEAD AND SILVER. 191 



SOUTH DAKOTA. 



2.08.18. Example 30/. Galena (town), in the Black Hills. 

 Contact deposits of galena, in part altered to carbonate, in Car- 

 boniferous limestone along intruded porphyries. The ore occurs 

 in the Carboniferous limestone, which overlies the Potsdam sand- 

 stone near Deadwood, in the northerly flank of the Black Hills. 

 The principal localities are the towns of Galena and Carbonate. 

 Sheets and dikes of igneous rocks penetrate the limestones and 

 have occasioned the ore deposits. Several smeltery have had some- 

 what desultory campaigns. 1 



MONTANA IDAHO. 



2.08.19. Example 32. Glendale, Beaver Head County. Ore 

 bodies of argentiferous galena, zincblende, copper and iron pyrites, 

 and their oxidation products, occurring parallel with the stratifica- 

 tion planes of a blue-gray limestone, of age not yet determined. 

 These deposits constitute the Hecla mines, and are in the south- 

 western part of the State. They offer some parallel features with 

 those of southeastern Missouri. (Example 23.) They differ from 

 Example 30 in not being associated, so far as known, with igneous 

 rocks. 2 



2.08.20. Example 32a. Wood River, Idaho. Bodies of ar- 

 gentiferous galena and alteration products, irregularly distributed 

 in limestone, of age as yet undetermined. Southwestern Idaho is 

 largely formed of granite, southeastern is covered by the immense 

 fissure outpourings of basalt along the Snake River. North of 

 these, and on the flanks of the granite, are slates and limestones, 

 especially on the Wood River. The latter contain the lead-silver 

 ores. They are not in immediate association with igneous rocks, 

 and from published descriptions appear to be somewhat irregu- 



M. E., XVIII. 261. S. F. Emmons, "Notes on Some Colorado Ore De- 

 posits," Proc. Colo. Sci. Soc., Vol. II., Part II., p. 97. M. C. Ihlseng, "Re- 

 view of the Mining Interests of the San Juan Region," Ann. Rep. Colo. 

 Schoql of Mines, 1885, p. 46. T. E. Schwartz, "The Ore Deposits of Red 

 Mountain, Colorado," M. E., June, 1889 ; Proc. Colo. Sci. Soc., Vol. III.,. 

 Part I., p. 77. 



1 F. R. Carpenter, " Ore Deposits of the Black Hills of Dakota," M.E.,. 

 1879, New York meeting. See also report by Dr. Carpenter on the geol- 

 ogy, etc., of the Black Hills, to the trustees of the Dakota School of Mines, 

 1888, p. 124. S. F. Emmons, Tenth Census, Vol. XIII., p. 91. 



2 S. F. Emmons, Tenth Census, Vol. XIII. , p. 97. 



