﻿I860.] 



FORBES — BOLIVIA AXD PERU. 



31 



and the Tofos mapped on M. Domeyko's geological map of Chile in 

 the ' Annales des Mines ' * pertain to the former. Both of these 

 classes can he seen at many points in the district here treated of, and 

 -will be subsequently noticed. 



This rock is occasionally itself metalliferous, as at El Cobre in the 

 Desert of Atacama, where the diorite is very strongly impregnated 

 with sulphurets of iron and copper. We always find, however, that 

 the fissures or faults formed in the neighbouring strata by the pro- 

 trusion of the diorite are converted into metallic veins by the injec- 

 tion of metallic compounds of sulphur and arsenic ; and a very careful 

 examination has shown that the metallic veins of the Oolitic and 

 Porphyry series of Chile, Peru, and Bolivia, which constitute the 

 great source of mineral wealth of these countries, are all due to the 

 appearance of this rock. The silver-mines of Huantajaya and the 

 copper-mines of Paposo, El Cobre, Cobija, Gatica, Tocopilla, La 

 Portada, and the veins of iron- and auriferous pyrites frequently met 

 with, are all of this origin. 



In these mineral veins I have found the following metallic com- 

 pounds to occur : — 



Native Gold. Silver-glance. 



„ Silver. Galena. 



„ Antimony. Zinc-blende. 



„ Bismuth. Copper-glance. 



„ Arsenic. Copper-pyrites. 



„ Copper. Erubescite. 



Arquerite. Cuproplumbite. 



Amalgam. Stromeyerite. 



Bismuthic Silver. Iron-pyrites. 



Magnetite. Marcasite. 



Specular Oxide of Iron. Covelline. 



Domeykite. Molybdenite. 



Darwinite. Mispickel. 



Algodonite. Danaite. 



Discrasite. Glaucodot. 



Copper-nickel. Pyrargyrite. 



Cobaltine. Proustite. 



Bealgar. Enargite. 



Stibnite. Tennantite. 

 Sulphuret of Bismuth. 



And further, from the oxidation of the above minerals, the action of 

 the carbonic acid in the atmosphere, and the elements in the salts 

 contained in the sea (under which this country has been submerged 

 since the appearance of these veins), we also find the following 

 minerals subsequently produced : — 



Malachite. Condurrite. 



Azure Copper. Silicate of Copper. 



Atacamite. „ of Copper and Manganese. 



Sulphate of Copper. Oxide of Copper. 



„ of Iron. Chloride of Silver. 



Iron-alum. Chlorobromide of Silver. 



Manganese-alum. Bromide of Silver. 



Botryogen. Iodide of Silver. 



* Quatrieme serie, vol. ix. 1S4G. 



