442 The Andes and the Amazons. 



have been found on the surface of tlie plain, one weighing 

 800 pounds. Rich deposits occur also in the province of 

 Cailloma, north of Arequipa ; and at Yauli, San Mateo, and 

 other localities near the Oroya Railroad. Extensive veins 

 have been recently discovered at Chilete, the terminus of 

 the Pacasmayo Railroad, the ore assaying from $60 to 

 $200 a ton. A Bostonian has a large interest in this mine. 

 Silver associated with gold and copper is found in the 

 Cerro Potoche, near Huancavelica. The mines of Hual- 

 langa, near Tarma, have yielded 3000 marks in a year. 



But the most numerous and promising silver-mines of 

 Peru are, without doubt, located in the department of Au- 

 cachs, just north of Lima ; not because it is a richer region 

 than the eastern cordillera, but because it is the only dis- 

 trict which has been scientifically explored. This has been 

 done by the accomplished naturalist. Professor Raimondi, 

 under the patronage of Mr. Henry Meiggs. The i-eport 

 recently published at Lima contains assays of specimens 

 from the most valuable mines in which the silver occurs. 

 It appears : (1) That silver is not very common in the na- 

 tive state. (2) That the minerals richest in silver are py- 

 rargyrite ((rosicler, or ruby silver) and stephanite (brittle 

 silver glance). (3) That the greater part of the silver, 

 however, is extracted from tetrahedrite, galena, and many 

 mineral oxides {pacos or colorados). The pacos richest 

 in silver ore are those which result from the oxidation of 

 stephanite and pyrargyrite ; the poorest are found in great 

 part of oxide of iron, in which the silver is minutely dis- 

 seminated in the native state. (4) It is worthy of notice 

 that the silver ores are constantly associated with antimo- 

 ny. Even the galenas, having a cubical structure, always 

 contain a small percentage of antimony. In general, it 

 may be said that the silver of Peru, as of Chile and Bo- 

 livia, whether native or in the form of chloride, sulphide, 



