Angola and the River Congo, vol. 1

by Joachim John Monteiro

Two kinds of clay are found, a ferruginous red, and an unctuous black variety. The malachite occurs almost entirely in the former. A large proportion was obtained in the form of small irregularly-shaped shot, by washing the clay in suitable apparatus. Large quantities had been raised by the natives from this valley before the country was taken possession of by the Portuguese.

For about fifteen years previously, as before stated, from 200 to 300 tons per annum had been brought down to Ambriz by the natives for sale. The mining captain sent out by the English Company did not judiciously employ his force of miners in properly exploring the deposit, so that its extent was never fully ascertained; no shafts were sunk to more than six or eight fathoms in depth at the bottom of the valley, from the quantity of water met with, but in several places the bottom of these shafts was found to be pure solid malachite. In no case was malachite ever found in the clay-slate rock of the country, and there can be no doubt that this vast deposit was brought and deposited in the valley by the agency of water. No other mineral is to be found in the valley, and only some rounded, water-worn pieces of limestone were found in the clay and associated with the malachite.

In some pieces of this a few crystals of atacamite are to be rarely seen. The clay-slate is completely bare of minerals,—with very few veins of quartz, which is highly crystalline,—has well-defined cleavage planes, with a strike of N.W. by S.E., and dips to the S.S.W. at an angle of about 55°.

In no part of Angola, except at Mossamedes, have any regular lodes or deposits of copper or other metals (except iron) been found in situ; all bear unmistakable evidences of having been brought from elsewhere, and deposited by the action of water in the places where they are now found.

I have no doubt that the country farther to the interior will be found immensely rich—in copper principally—where the lodes most likely exist that have supplied the enormous amount of copper carbonates found all over Angola, and farther north at Loango.

Some idea may be formed of the great extent of the Bembe deposit, if we consider the manner in which the natives formerly extracted the malachite. It was entirely by means of little round pits, about three or four feet in diameter, sunk in the bottom of the valley and along its whole length, particularly at several places where the water draining from the country above had washed away the clay, and formed little openings on the same level as the bottom of the valley. When I arrived at Bembe, many of these pits were still open for a couple of fathoms deep, as many as eight or nine pits being sunk together in a rich spot. They sunk them only in the dry season, and as deep as four or five fathoms, but of course they were never carried down quite perpendicularly, but in an irregular zigzag fashion, and not being timbered they often fell together, and numbers of blacks were buried alive in them every year. We several times came across bones of blacks who had thus lost their lives. During the rainy season, of course, these pits were filled up with water and mud, and fresh ones had to be dug in the succeeding dry season.

To ascend and descend them the natives drove wooden pegs into the walls, and their only mining tools were the little hoes used in clearing and cultivating the ground, and the cheap spear-pointed knives, ten or eleven inches long, they received in barter at Ambriz from the traders.

The mines belonged to several of the towns in the immediate neighbourhood, principally to one called Matuta; but they allowed the natives of other towns to extract malachite from them, on payment of a certain quantity of the ore they raised.

The natives of Ambriz who went up to Bembe to buy malachite of the Mushicongos were seldom allowed to pass the River Luqueia, where the malachite was brought down for sale by measure, in little baskets, being like the red gum copal, broken into moderate-sized pieces, except the finer lumps, which were sold entire. Most of the malachite has since been obtained by means of levels driven into the side from the bottom of the valley, but the great mass, below the level at which water is reached, remains practically untouched.

The failure of the English Company, from causes to which it is here unnecessary further to advert, caused the works at the mines to be gradually abandoned, and for the last few years the Portuguese have allowed the blacks to work them in their own fashion again; and I was very sorry to see the place in a complete state of ruin, with only a few stone walls overgrown with a luxuriant growth of creepers and other plants to mark the places where the houses and stores formerly stood, and where several hundred natives used to be daily at work.