94 THE MINERALS OF CHILE. 



Native Silver. — This is found, in more or less abundance, in the various silver mines ot 

 Chile. Most frequentlj' it is associated with dolomite^, calcareous spar, sulphate of baryta, and 

 some of the minerals of cobalt. Much of it is found in the form of thin sheets, as at San Pedro 

 Nolasco ; at Calaba^o (Illapel) it is in small irregular grains ; and at various mines in Copiapo 

 it exists in the form of threads, along with native arsenic and other arsenical minerals. At 

 Chaiiarcillo it occurs associated with the chloro-bromides, in dendritic forms ; and at San 

 Antonio, and some other mines, it is found in both small and large grains, in afseniuret of 

 copi^er and arseniuret of cobalt. At Illapel it is found in red oxide of copper. 



Silver Glance, Sulplmret of Silver. — This mineral occurs in all the mines of silver, although 

 in no considerable quantity, and is rarely if ever crystallized. It is of a black lead color, of a 

 metallic lustre, having a specific gravity of 7.3, and is readily reduced, on a piece of charcoal, 

 by the action of the blow-pipe. Its composition is — 



Silver 85 



Sulphur - - - - - - - 15 



100 



Its formula is Ag S. 



Sulplmret of Silver and Copper. — This compound is made mention of by M. Domeyko as exist- 

 ing in the mines of San Pedro Nolasco and Catemo. His analysis gave the following, as its 

 constitution : 



San Pedro Nolasco. Catemo. 



Silver 28.8 24.1 16.6 12.1 



Copper ----- 53.4 53.9 GO. 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 consider it merely a mixture of silver 

 and copper glance. 



Buhy 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 furnishes silver under the 

 blow-pipe, when heated on charcoal. Its most constant companions are native arsenic, arseniuret 

 and sulpho-arseniuret of iron, arsenical cobalt, blende, calcareous spar, silver glance. It is 

 sometimes found crystallized in metastatic dodecahedrons ; at other times it is in masses dis- 

 seminated 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 Chaiiarcillo in the lower part of the veins, and in other 

 mines in the jirovince of Atacama. 



There are two distinct compositions to the dark and light ruby silver; the former being a sul- 

 phuret 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 -I- Sb S^ 



