160 RE-EXAMINATION OF AMERICAN MINERALS. 



size, weighing three or four hundred pounds. Fine crystals 



are obtained, both tetrahedral and octahedral. It affords on 



analysis 



Sulphur 36.10 



Copper 32.85 



Iron 29.93 



Lead 35 



99.23 



It occurs alone and associated with the other sulphurets. 

 It is found in various parts of the vein, there being no special 

 point of deposit. 



57. Malachite. 



Malachite occurs in small reniform masses, consisting of 



fibrous crystals, and of a bright-green color; also in silky tufts 



of a very light-green color, which are associated with azurite 



and carbonate of lead. Its specific gravity is 4.06. An analysis 



gave 



Carbonic acid 19.09 



Oxide of copper 71.46 



"Water 9.02 



Oxide of iron 12 



99.69 



affording the formula CuC+CuH. It is associated with the 

 various ores of copper and lead of the Wheatley Mine, and 

 sometimes so thoroughly diffused through the sulphate and 

 carbonate of lead as to give them a uniform green tint. It is 

 not found in any quantity. 



58. Azurite. 



This mineral, although rare, is found in beautiful crystals, 



some measuring from one fourth to one half inch across, of a 



deep-blue color, and highly polished faces. Its specific gravity 



is 3.88. An analysis gave 



Carbonic acid 24.98 



Oxide of copper 69.41 



Water 5.84 



100.23 



giving the formula 2CuC+CuH. This species occurs in similar 

 associations with the malachite; it is, however, rarer. 



