Peruvian method of Smelting. 233 



The mines of Huantajaya, are situated in the southern part of 

 Peru, near the Port of Yquique, in a low desert plain, entirely de- 

 prived of water. The ore is a decomposed mass, mingled with na- 

 tive silver, chloride and sulphuret of silver, and galena. It is ac- 

 companied by quartz and carbonate of lime. These mines are cel- 

 ebrated for the large masses of native silver found in them. One 

 mass weighed more than eight quintals. Rock salt occurs in abun- 

 dance in the vicinity of the mines. 



V. Mines of Potosi. 



These mines are situated in about 20° S. Lat. upon the eastern de- 

 clivity of the Andes, near the most elevated sources of the La Plata. 

 They were discovered in 1545, and had furnished, up to 1804, mora 

 than f 1,100,000,000. The first eleven years were most productive, 

 the annual produce during that time, being 1,300,000 pounds weight. 

 Many of the ores then gave from ^Vo to tVo ^^ metallic silver. In 

 1574, the ores produced from 4 to 4^'pev cent ; in 1607, 1 3'^ ounce 

 per quintal or j-^W ^ 5 ^^ the beginning of the eighteenth century, jVo 

 to tVo of ^^ ounce per quintal of ore. Thus, it seems that these 

 mines have lost in richness, as the excavations have been carried 

 deeper, but as the entire product of silver is not greatly diminished, 

 the quantity of ore, compensates for its poverty. In 1S04, Potosi 

 reported an annual product of 400,000 pounds weight of silver. 



The veins of ore, at the Potosi mines, traverse an argillaceous 

 slate, which forms the mass of the mountain, but the summit is 

 crowned by a bed of argillaceous porphyry, containing garnets. The 

 veins are very ntimerous, and some of them are elevated in the form 

 of a crest ; the rocks of the floor and roof having been more rapidly 

 decomposed than the vein. These crests were composed almost 

 entirely of red silver, sulphuret of silver, and native silver. One of 

 the veins, viz. del estano, presented for its crest, and even for a 

 great depth, only the sulphuret of tin, below which is found the chlo- 

 ride of silver. This is an example of two mineral formations in one 

 vein, similar to what has been observed in the Freyburg mines in 

 Saxony, and in the tin and copper mines in Cornwall, Eng. 



Peruvian method of smelting. 



The Peruvian method of reducing the silver ores, was to melt 

 them with galena, in broad circular clay furnaces, pierced with a great 

 number of holes, so that the free access of the exterior wind, might 



