68 MINERALS OF CHILE. 



SULPHURET OF SILVER AND COPPER. 



This compound is made mention of by M. Domeyko as 

 existing in the mines of San Pedro Nolasco and Catemo. His 

 analysis gave the following as its constitution : 



San Pedro Nolasco. Catemo. 



"~ 1 2^ '"~3 4 "^ 



Silver 28.8 24.1 16.6 12.1 



Copper 53.4 53.9 60.6 64.0 



Iron 0.0 2.1 2.3 2.5 



Sulphur 19.8 19.9 20.5 21.4 



100.0 100.0 100.0 100.0 



From the variable nature of its composition I should con- 

 sider it merely a mixture of silver and copper glance. 



RUBY-SILVER. 



It occurs both crystallized and massive, possessing a very 

 dark crimson-red color ; the color is commonly so intense that 

 the mass appears black except when examined by transmitted 

 light in thin pieces ; it is easily cut with the knife, and fur- 

 nishes silver under the blowpipe when heated on charcoal. 

 Its most constant companions are native arsenic, arseniuret 

 and sulpho-arseniuret of iron, arsenical cobalt, blende, calca- 

 reous spar, silver glance. It is sometimes found crystallized 

 in metastatic dodecahedrons; at other times it is in masses 

 disseminated in the midst of different spars and argillaceous 

 gangues. It is found in microscopic crystals in the cavities 

 and crevices of native arsenic and of arseniuret and sulpho- 

 arseniuret of iron. The principal sources of it are at Chanar- 

 cillo in the lower part of the veins, and in other mines in the 

 province of Atacama. 



There are two distinct compositions to the dark and light 

 ruby-silver; the former being a sulphuret of antimony and 

 silver, and the latter a sulphuret of arsenic and silver. 



Dark Ruby-Silver. 



Silver 58.98 



Antimony 23.46 



Sulphur 17.56 



100.00 

 The formula of this is 3 Ag S-fSb S 3 . 



