152 KEMP'S ORE DEPOSITS. 



2.04.26. There, are numerous other copper districts in Arizona, 

 of minor importance or entirely undeveloped, but the examples 

 above cited probably illustrate the occurrences quite fully. Those 

 not referred to above are of sporadic development. Mention 

 should also be made of the mines in Lower California, opposite 

 Guaymas, a brief description of which will be found in Wendt's 

 paper. 1 



2.04.27. Example 20g. Crismon-Mammoth, Utah. In the 

 Tintic district, Juab County, Utah, are three great ore belts, in 

 vertically dipping dolomitic limestone, as more fully set forth 

 under " Silver " (Example 35a). One of these, the Crismon-Mam- 

 moth, contains ores that bear silver, gold, and copper in propor- 

 tions of about equal value. They have been a very difficult 

 mixture to treat successfully. Of late considerable copper has 

 been produced, placing the ore deposits among those deserving 

 mention. The Crismon-Mammoth vein or belt covers a maxi- 

 mum width of 70 feet, and runs 500 feet on the strike, dipping 75 

 west. The ores seem to have been deposited along the bedding 

 planes, though often cutting across them. The productive por- 

 tions are found in richer chutes or chimneys, amid much low-grade 

 material and gangue, and are of all shapes and sizes, from 25 feet 

 in diameter, down. The Copperopolis is thought to be on the same 

 belt, and is a neighboring location of similar geological structure 

 and ores. 2 



2.04.28. Sunrise, Wyoming. Oxidixed ores have been ex- 

 ploited to some extent at the Sunrise mines, in the Laramie range, 

 Wyoming, but were never of much importance. 



2.04.29. Example 21. Copper ores in Triassic or Permian 

 sandstone. They occur as oxidized ores, native silver, and 

 chalcocite in contact deposits in Triassic and Permian sandstones 

 at their junction with diabase or gneiss, or as disseminated masses 

 replacing organic remains. Copper ores are very common 

 throughout the estuary Triassic rocks of the Atlantic coast, and 

 although formerly much mined, they are now proved valueless, and 

 of scientific interest only. 



2.04.30. Example 21a. Contact deposits in sandstone at its 



1 See also M. E. Saladin, "Note sur les Mines de Cuivre du Boles 

 (Basse Californie)," Bull, de la Societe de Vlndustrie Minerale, 3 Serie, 

 VI. 5, 283. 



2 O. J. Hollister, ''Gold and Silver Mining in Utah," M. E., XVI., 

 p. 10. D. B. Huntley, Tenth Census, Vol. XIII., p. 456. 



