Examination of a few American Minerals. 121 



The 1-294 grms. of silicate yielded by analysis : 



Water, . . 3429 grms. in 100 parts ; 26-50 



Silica, . . . 0-414 ' " " " 32-00 



Oxide of copper, . 0-4237 " " " 3j!-75 



Iron and alumina, 0-100 " " " 7'75 



1-2806 



99-00 



The following analyses are added for comparison : 

 1. Smith, Chili; 2. Field, Chili; 3. Joy, Copper Harbor; 

 4. Jackson, Copper Harbor; 5. Berthier, Somerville, N. J. 



2. Black Oxide of Copper. 



Some years ago I saw tons of this mineral excavated from a 

 bed in the conglomerate at Copper Harbor. The miners sup- 

 posed that the supply would prove inexhaustible, and com- 

 paratively few specimens were saved. Many rounded pebbles 

 of black oxide were found on the shore of the lake, and in the 

 mine; they presented a rounded or indented surface, not 

 unlike many metallic meteorites. 



Whitney* found for the specific gravity of a very pure spe- 

 cimen, 6-25. Another specimen gave me 5-952.f 



I analysed three specimens with the following result : 



* Report II, 100. 



f Pogg. Ann. LXXX., 286. 



