I860.] on the Mineral Treasures of the Andes, 191 



and sulphur. 3. Combinations of copper with arsenic, or with arsenic 

 and sulphur, or antimony and sulphur. 



In the first division are found many interesting varieties. The 

 native copper of Chili, found not only in the higher ridges of the 

 Cordilleras, but also comparatively near the coast,' is remarkable for its 

 purity. In the district of Andacollo, a few leagues east of Coquimbo, 

 it occurs in large masses, containing sometimes merely traces of 

 foreign matter, among which gold is generally recognized. The red 

 and black oxides are found associated with the metal, the former in 

 larger quantity, in fine crystals belonging to the regular system, and 

 having a clear ruby colour. The black oxide, hitherto considered a 

 rare mineral, has quite recently been observed in the extreme north of 

 Chili, as a fibrous mass, somewhat resembling hornblende. 



The carbonates of copper abound extensively in the Andes, 

 although no true malachite has yet been discovered, at least which 

 will bear comparison with the specimens met with in Russia, Australia, 

 and the west coast of Africa. The silicates, black, blue, and green are 

 abundant ; the two last varieties are termed llanca, by the miners ; they 

 do not occur crystallized, but in masses, sometimes assuming the 

 botryoidal form. A rare double silicate of manganese and copper has 

 also been obtained, easily soluble in hydrochloric acid, even in the 

 cold, with evolution of chlorine. This mineral is called by the miners 

 " metal de carhon^^ from its striking resemblance to ordinary coal. 



The phosphates of copper, Tagilite (4 Cu O, P O5, 3 H 0) and 

 Liebethenite (4 Cu O, P O5, H O) have only lately been described. 

 They were discovered in a mine in Tamhillos, near Coquimbo. A 

 very rare double phosphate of lime and copper occurs in the same dis- 

 trict 2 (6 Cu O, P O5) + 10 (3 Ca O, P O5 + Ca CI) ; it is found 

 associated with apatite in large blueish-green crystals. 



Atacamite derives its name from the locality in which it was 

 originally discovered, the desert of Atacama. It has been recognised 

 as far south as Coquimbo, although only occasionally. Nearly all the 

 mines in the district north of Copiapo, on the confines of Bolivia, 

 yield this mineral. It consists of Cu CI, 3 Cu O + 4 H O. * Berthier 

 analyzed a specimen from Cobija, containing six atoms of water. 

 Atacamite was produced artificially in some smelting works in Chili, 

 in very large quantities. Pounded oxide of copper, the product of 

 calcined regulus in a fine state of division, gradually accumulated upon 

 the base of a horizontal chimney close to the sea. The floor of the 

 chimney had not been bricked, but consisted simply of sand impreg- 

 nated with the alkaline chlorides and sulphates. The hot oxide of 

 copper, partially protected by additional layers of dust from the 

 furnace, by long contact with the sand became converted, after the 

 lapse of some months, into sulphate and oxy-chloride of the metal. 

 More than three tons were accidentally obtained in this manner. 



Double sulphides of copper and iron : — Disulphide of Copper ex- 

 ists very often iu a state of great purity, containing sometimes 

 79 ■ 5 of metal, with scarcely a trace of iron. The proto-sulphide is 



