MINERALS OF CHILE. 67 



is most commonly traversed by copper-veins, sometimes of a 

 considerable size. Along the coast it is found in the form of 

 copper pyrites alone, or associated with two varieties of iron 

 pyrites, and also as peacock or purple copper. Galena and 

 blende are rarely found in them, and scarcely ever gray copper. 

 Native copper, red oxide, oxychloride, oxysulphuret, green car- 

 bonate, and hydrous and anhydrous silicates of copper of a great 

 variety of colors are also abundant, especially at the upper part 

 of the veins. The silicates sometimes line the walls of the veins, 

 and penetrate to some distance in the inclosing rock, which be- 

 comes unequally colored blue or green. The numerous veins of 

 copper are disseminated very irregularly in the granite, and 

 their value is equally variable; sometimes the veins have a 

 breadth of from six to nine feet, as at Tamaya, near Coquimbo, 

 where at the depth of six hundred feet there is a dail}' yield of 

 from eight to ten tons of an ore yielding seldom less than fifty 

 and oftentimes as much as seventy-five per cent, of copper. 



NATIVE SILVER. 



This is found in more or less abundance in the various 

 silver-mines of Chile. Most frequently 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 Calabaco (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 Chanarcillo it occurs associated 

 with the chloro-bromides, in dendritic forms ; and at San An- 

 tonio and some other mines it is found in both small and large 

 grains in arseniuret of copper and arseniuret of cobalt. At 

 Illapel it is found in red oxide of copper. 



SILVER GLANCE, SULPHURET 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 luster, having a specific 

 gravity of 7.3, and is readily reduced, on a piece of charcoal, 

 by the action of the blowpipe. Its composition is 



Silver 85 



Sulphur 15 



Its formula is As S. 10 ° 



