284 MINES 



or an ounce and -j per cwt. ; although some occur -which yield 30 or 40 per cent 

 These rich deposits do not seem to be extended to a great depth ; they hare not been 

 pursued farther than 1 30 yards, and in the greater part of the workings only to from 

 85 to 45. Forty years ago, these mines, which produced nearly 2,000,000 of piastres 

 annually, were the worst worked in all South America. The soil seems as if riddled 

 with an immense number of pits, placed without any order. The drainage of the 

 waters was effected by the manual labour of men, and was extremely expensive. In 

 1816, some Europeans, among whom were several miners from Cornwall, erected, 

 under the direction of the celebrated Richard Trevithick, several high-pressure steam- 

 engines, imported from England, and introduced a considerable improvement in the 

 workings. 



The total yield of Peru is estimated at about 300,000 Ibs. troy per annum. 

 The mines of the province of Chota are situated in about seven degrees of south 

 latitude. The principal ores are those of Gualcayoc, near Mecuicampa, discovered in 

 1771; their outcrop occurs at the height of 4,500 yards above the sea; the city of 

 Mecuicampa itself has 4,000 yards of eievation, that is, higher than the highest sum- 

 mits of the Pyrenees. The climate is hence very cold and uncomfortable. The oro 

 is a mixture of sulphuret of silver and antimoniated sulphuret, with native silver. 

 It constitutes veins of which the upper portion is formed of pacos, and they some- 

 times traverse a limestone and sometimes a hornstone, which occurs in subordinate 

 beds. The annual produce of the mines is 67,000 marcs of silver, according to 

 Von Hutnboldt. 



In the districts of Huaailas and Pataz, which are at a little distance from the former 

 two, gold mines are worked. This metal is extracted -chiefly from tho veins of quartz, 

 which run across the primary schistose mountains. The district of Huaailas con- 

 tains also lead mines. Peru possesses, moreover, some mines of copper. 



The quicksilver mine of Huancavelica, long the only important mine of this species 

 which was worked in the New World, occurs on tho eastern flank of the Andes of 

 Peru, in 13 degrees of south latitude, at upwards of 6,000 yards above the level of the 

 sea. It does not seem referrible to the same class of deposits with the mines hitherto 

 mentioned, but occurs in sandstones and shales, apparently of the carboniferous period. 

 Indications of mercurial ores have been observed in several other points of tho 

 Andes of Northern Peru, and the south of New Granada. 



Deposits of rock salt are known to exist in Peru, especially near the silver mines of 

 Huantajaya ; and nitrate of soda is found in large quantity in the desert of Tarapaca. 

 On receding from the district of Chota. the Cordilleras are less abundantly stored 

 with metallic wealth, to the isthmus of Panama, and even far beyond it. Tho kingdom 

 of New Granada offers but a very small number of silver mines. There are some auri- 

 ferous veins in the province of Antioquia, and in the mountains of Guamoco. The pro- 

 vince of Caracas, the mountains of which may bo considered as a ramification of the 

 Cordilleras, presents at Aroa a copper mine which furnishes annually from 700 to 800 

 metric quintals (1,400 to 1,600 c\vts.) of this metal. Finallj 7 , we may state in passing, 

 that there is a very abundant salt mine at Zipaquira, in the province of Snnta-Fe, 

 and that between this point and the province of Santa-Fe-de-Bogota, a coal-field occurs 

 at the extraordinary height of 2,700 yards. Emeralds are worked at Muzo. 



Although Mexico presents a great variety of localities of ores, almost the only ones 

 worked are those of silver. Nearly the whole of these mines are situated on the back 

 or the flanks of the Cordilleras, especially to the west of the chain, at tho height of 

 the great table-land which traverses this region of the globe, or a little below its 

 level in the chains which divide it. They lie in general between 2,000 and 3,000 yards 

 above tho sea; a very considerable elevation, which is favourable to their prosperity, 

 1 H'Ciiuse in this latitude there exists at that height a mean temperature mild, salubrious, 

 and most propitious to agriculture. There wore at the time of Humboldt's visit, from 

 4,000 to 5,000 deposits of ore exploited. Tho workings constituted 3,000 distinct mines, 

 which were distributed round 500 head-quarters or Stales. Those mines are not, how- 

 ever, uniformly spread over the whole extent of tho Cordilleras. They may be consi- 

 dered as forming eight groups, which altogether do not include a greater space than 

 12,000 square leagues; viz. hardly more than tho tenth part of the surface of Mexico. 

 These eight groups are, in proceeding from south to north, 



1 . Tho group of Oaxitaca, situated in tho province of this name at tho southern extre- 

 mity of Mexico properly so called, towards tho 17th degree of north latitude, licsi.h's 

 silver mines, it contains the only veins of gold explored in Mexico. These veins tra- 

 verse gneiss and mica-slate. 



.. 2. The group of Tasco. Tho most part of tho mines which compose it arc situated 

 20 or 25 leagues to tho south-west of Mexico, towards the western slope of the great 

 plateau. 



3. Tho group of Biscania, about 20 leagues north-east of Mexico. It is of moderate 



