In various other parts of the Capitania, gold wash ings are established, at some of which gold is found of a very fine quality. Diamonds have been col lected in enme parts, which are more brilliant in their appearance than those found in the diamond districts of Cerro do Frio, but are not generally of so pure a water. It is known that the river Das Mortes, which belongs to the Capitania of Matto Grosso, and flows in a large stream into the Aragua from the west, is auriferous ; and, according to the experience of those most skilled in the nature of the country, the smaller streams which descend from the higher grounds, must be still more produce tive of gold. Some mining works were at one time established in these remote districts, which were abandoned, not from any scarcity of gold, but because the few inhabitants who had settled in the country, being far removed from the road, and in the midst of a swamp inhabited by savages, could nei ther be conveniently supplied with arms for their defence, nor with implements for their trade. Far. ther to the west is found the river Cuiaba, and the other head waters of the river Paraguay, all of which produce gold. The mines of Cuiaba are established on the river of this name, and near the town of Cui aba, which is large, and is estimated to contain 30,000 inhabitants. They were discovered in the year 1718, and were long celebrated for the quanti ty of gold which they produced, which has been calculated at 20 arrobas (500 lbs.) annually. The metal is also said to be of an extremely fine, quality. The head waters of all the other great rivers, such as the Chingu, the Topayos, and the Madera, which rise in this Capitania, and flow into the Amazons, are found to produce gold. On the river Arinos, which is a western branch of the Topayos, some establishments for collecting gold were begun in 1747. But they were afterwards abandoned, chiefly in consequence of the dangers to which the adven turers were exposed from the tribes of warlike In dians by which this country is infested. The inve terate hostility of the native tribes to the Portuguese, tends greatly to obstruct the progress of new set tlements ; as a body of adventurers must be col lected sufficiently numerous to protect themselves against their savage enemies, before any settlement can be begun ; and, even in this case, being in a state of perpetual watchfulness and alarm, their at tention is continually distracted from agriculture or mining, to the more necessary business of war. But where the country is known to abound in gold or diamonds, adventurers soon crowd from all quarters to gather the rich harvest ; the barbarous inhabitants are driven back into the desert ; towns and villages arise ; roads are opened ; and the country arourd quickly assumes the appearance of cultiyation and improvement.
The gold which is collected in Brasil, is found either in deep valleys or in the channels of rivers. It is generally contained in a loose marl-like stratum of rounded quartose pebbles and adventitious mat ter, called cascalhao, which rests upon granite, and is covered by earthy matter of variable thickness. Sometimes the gold is found covered by the soil at Nee depth of tO feet, while at other times, on many of the hills where water can be collected for washing, particles of gold appear in the soil at little greater alepth than the roots of' the grass.
At the gold washings of Villa Rica, the bed of eascalhao was on the margin of the river ; and Mr Mawe found the workmen engaged in cutting away the bank to the depth of, at least, 10 feet, before they could reach the vein containing the gold which was incumbent on the rock. The substance they had to cut through was clay, so strong that, though falls of water were precipitated upon it, and negroes were constantly working it with hoes of various kinds, it was with difficulty removed. Nor was this the only impediment ; .for, by the continual washing down of mud from the higher grounds, the casealltho was five feet lower than the bed of the river, so that when the pits were sunk to its depth, they were soon filled with water, which had to be drawn of by means of machinery.
When the stratum which contains the gold is found at a distance from the rivers, it is dug up and carried to a convenient place, where it is washed, for the purpose of separating the earth and other materials from the gold. The method of wash ing it is simple, and the following account of it is given by Mr Mawe, who• was freely permitted to visit the different gold-washings established in the -country.
" Where water" (he observes) " of sufficiently high level can be commanded, the ground is cut in steps, each twenty or thirty feet wide, two or three broad. and about • one deep. Near the bottom a trench is cut to the depth of two or three feet. On each step stand six or eight negroes, who, as the water flows gently from above, keep the earth con. tinually in motion with shovels, until the whole is reduced to liquid •mud, and washed below. The particles of gold contained in this earth descend to the trench, where, by reason of their specific gravity, they quickly precipitate. Workmen are continually employed at the trench to remove the stones and and clear away the surface,—which operation is much assisted by the current of water which falls into it. After five days washing, the precipitation
in the trench is carried to some convenient stream, • to undergo a second clearance. For this purpose wooden• bowls are provided, of a funnel shape, about two feet wide at the mouth, and five or six inches deep, called gariellas. Each workman, standing in the stream, takes into his bowl five or six pounds weight of the sediment, which generally consists of heavy matter, such as oxide of iron, pyrites, ferru ginous quartz, &c. of a dark carbonaceous hue. They admit certain quantities of water into the bowls, which they move about so dexterously, that the pre cious metal, separating from the inferior and lighter substances, settles to the bottom and sides of the vessel. They then rinse their bowls in a larger yes sel of clean water, leaving the gold in it, and begin again. The washing of each bowlful occupies from five to eight or nine minutes ; the gold produced is extremely variable in quantity, and in the size of its particles ; some of which are so minute that they float, while others are found as large as peas, and not nnfrequently much larger. This operation is super intended by overseers, as the result is of considerable importance." There is another mode of separating the gold from the casco/aao, which is described in the follow ing manner: " Two planks about ten or twelve inches broad and about twelve or fifteen feet in length, are laid in the ground; forming an inclined plane, slop ing one inch in twelve ; two other planks, of similar dimensions, are fixed in the same direction at the lower end, forming a second inclined plane, with a fall of six inches from the former. On their sides are boards placed edgewise, and staked down to the ground, so as to form long shallow troughs, the bot toms of which are covered with hides tanned with the hair on, having the hairy side outwards, or, in defect of these, with rough baize. Down these troughs is conveyed the water containing the oxide of iron and the lighter particles of gold ; the latter substance precipitating in its course is entangled by the hair. Every half hour the hides are taken up, and carried to a tank near at hand, formed of four walls, say five feet long four broad and four deep, and containing about two feet depth of water. The hides are stretched over this tank and well beaten, then dipped, and beaten repeatedly, until all the gold is disentangled, after which they are carried back and replaced in the troughs. The tanks are locked up at night, and well secured. The sediment taken from them being light, is easily washed away by the hand, in the manner before described, leav ing only the black oxide of iron, called camera, and the gold, which is so fine that mercury is used to separate it." In all those various operations of digging up the cuicalario, of removing it to a convenient place, and, finally, of washing away the earth from the gold, a great deal of time and labour is wasted which might be saved by adopting some very simple contrivances. In removing the earth, for example, to the place where it is to be washed, not a cart or a wheelbar row is used. The whole is transported in bowls, which are carried on the heads of poor negroes, who have frequently, with these heavy burdens, to climb ascents, where various methods might be opted with little trouble or contrivance, to abridge this unnecessary labour. The hydraulical appara tus, in use for draining of the water, is cum bersome and expensive. In many cases, ordinary pumps would answer the purpose better, as they can be made at little trouble and expence, are easily re paired, and can always be ready to work at an hour's notice. It is singular, that this very common and simple machine should be utterly unknown in those parts. The method practised in washing the casco& hao in bowls, is extremely tedious, and might be easily shortened. Great advantages would also be derived from the use of properly constructed mills for breaking down the hard substances which con tain gold, and which might then be washed in the same manner as the softer matter. We are inform ed by Humboldt, that, in the silver mines of Mexi co, this operation is executed with admirable skill, and with great advantages.* The hardest substances, previous to their amalgamation, are reduced to a fine powder; by which process every particle of the precious metal which they contain is carefully extracted. Those who are employed in washing for geld in Brasil, are exposed to various die advantages from the scarcity and high price of iron ; and owing to this circumstance they are frequently in want of the most ordinary tools. This fact strikingly illustrates the indolence and want . of enterprise which generally prevails in this coun try. A blind pursuit after geld seems to be the ex • elusive occupation of all classes, in favour of which the most valuable resources of the country are neglected. In many parts iron-ore is produced in abundance, and *here is little doubt that, if any spirited individual were to devote his attention to this branch of indus try, he would not only facilitate the acquisition of the precious metals, but he would more rapidly quire wealth, than if he were directly seeking after it by establishing gold-washings.