170

MINES.

nearly the 20tli degree of south latitude, on the eastern slope of the chain, and severalother districts, likewise very rich, which extend principally toward the northwest, asfar as the two banks of the lake Titicaca , and even beyond it, through a total length olnearly 150 leagues. All these districts, which formerly depended on Peru , were unitedin 1778 to the government of Buenos Ayres. The mines of Potosi were discovered in1545, and have furnished since that period till our days, a body of silver which M. Hum'boldt values at 230,000,000z. sterling. The first years were the most productive. Atthat time ores were often found which afforded from 40 to 45 per cent, of silver. Sincethe beginning of the eighteenth century, the average richness of the ore does not exceedabove from 3 to 4 parts in 10,000. These ores are therefore very poor at the presentday; they have diminished in richness in proportion as the excavations have becomedeeper. But the total product of the mines has not diminished in the same propor-tion : abundance of ore having made up for its poverty. Hence, if the mountain olPotosi is not, as formerly, the richest deposite of ore in the world, it may, however, bestill placed immediately after the famous vein of Guanaxuato . The ore lies in veins ma primitive clay state, which composes the principal mass of the mountain, and is cov-ered by a bed of clay porphyry. This rock crowns the summit, giving it the form of abasaltic hill. The veins are very numerous ; several, near their outcrop, -were almostwholly composed of snlphuret of silver, antimoniated sulphuret of silver, and nativesilver. Others, which offered near the surface merely sulphuret of tin, became richc{as they descended. In 1790, seven copper mines were known in the viceroyaltyBuenos Ayres, seven of lead, and two of tin; the last being merely washings of sandsfound near, the river Oraro.

On the opposite flank of the chain, in a low, desert plain, entirely destitute of watch'which adjoins the harbor of lquiqua, and forms a part of Peru , occur the silver minesof Huantajaya, celebrated for the immense masses of native silver which have beensometimes found in them. In 1758, one was discovered weighing eight cwts.

M. Humboldt quotes 40 cantons of Peru as being at the present day most famonsfor their subterranean explorations of silver and gold. Those of gold are found in tn‘provinces of Huaailas and Pataz ; the silver is chiefly furnished by the districts °/Huantajaya, Pasca, and Chota, which far surpass the others in the abundance of th e11ores. r

The silver mines of the district of Pasco are situated about 30 or 40 leagues north 0Lima, in 10J degrees of south latitude, 4,400 yards above the sea-level, on the eastWslope of the Cordilleras, and near the sources of the river Amazon. They were dj*covered in 1630. These mines, and especially those of Cero of Yauricocha, are actual •the richest in all Peru . The ore is an earthy mass of a red color, containing much ir° ■mingled with particles of native silver, horn silver, &c., constituting what they call P® c0 jAt first, nothing but these pacos was collected; and much gray copper and antimonia*^sulphuret of silver were thrown among the rubbish. The mean product of all the oresji ; or an ounce and ? s p er C wt.; although some occur which yield 30 or 40 P

] 2 5 0 ( 1 Uu w # - n oI

cent. These rich deposites do not seem to be extended to a great depth ; they hav ebeen pursued further than 130 yards, and in the greater part of the workings old!from 35 to 45. Forty years ago, these mines, which produced nearly 2,000,000 ol P y.tres annually, were the worst worked,in all South America . The soil seemed aS j.riddled with an immense number of pits, placed without any order. The drainage j nthe waters was effected by the manual labor of men, and was extremely expensive. _1816, some Europeans, among whom were several miners from Cornwall , mountederal high-pressure steam-engines, imported from England, which introduced a coerable improvement in the workings. thlati"

The mines of the province of Chota are situated in about seven degrees of s . ,771:tude. The principal ones are those of Gualcayoc, near Mecuicampa, discovered intheir outcrop occurs at the height of 4,500 yards above the sea; the city of Mecu lC e .itself has 4,000 yards of elevation, that is, higher than the highest summits v^ureof sU rnees. The climate is hence very cold and uncomfortable. The ore is a mixture ^phuret of silver and antimoniated sulphuret, with native silver. It constitutes ye > nf ,which the upper portion is formed of pacos, and they sometimes traverse a fim 0 fand sometimes a hornstone, which occurs in subordinate beds. The annual prothe mines is 67,000 marcs of silver, according to Humboldt . form er

In the districts of Huaailas and Pataz, which are at a little distance from the rt z.two, gold mines are worked. This metal is extracted chiefly from the veins 0 ’y 9 ; n s,which run across the primitive schistose mountains. The district of Huaailas cbesides, lead mines. Peru possesses, moreover, some mines of copper. whi c *'

The quicksilver mines of Huancavelica, the only important mine of this speci p cr o.has been worked in the New World, occurs on the eastern flank of the a n ‘,'i’.. Hin 13 degrees of south latitude, at upward of 6,000 yards above the level of ,^011®^’does not seem referrible to the same class of deposites with the mines hitherto m