The preceding notes show that the natives of the Gold Coast, and of West Africa generally, are adepts at procuring their gold by 'surfacing,' washing with the calabash or wooden bowl the rich alluvial formations that underlie the top-soil. This is the rudest form of machinery, preceding in California the cradle, the torn, and the sluice. Westerns made their pans of brass or copper, about sixteen inches in diameter, and nearly two inches deep in the middle where the gold gravitates. Panning in Africa is women's work, and the process has been described in the preceding pages.
But the natives, as has been shown, can also work quartz, an art well known to the Ancient Egyptians. They either pick up detached pieces showing visible gold, or they sink pits and nibble at the walls of the reefs. But whereas the Nile-peoples pounded the stone in mortars and washed the dust on sloping boards, here the matrix must be laboriously levigated. A handful of broken quartz is placed upon the 'cankey-stone,' with which the gudewife grinds her 'mealies.' It is a slightly hollowed slab of granite or hard conglomerate, some two feet square, sloping away from the worker, and standing upon a rude tripod of tree-branches secured by a lashing of 'tie-tie.' The stuff is then rubbed with a hand-stone not unlike a baker's roll, and a slight deviation is given to it as it moves 'fore and aft.' The reduced stone is caught in a calabash placed at the lower end of the slab. This is usually night-work, and all the dark hours will be wasted in grinding down a cubic foot of stone.
The late M. Bonnat had probably read Mr. Andrew Swanzy's evidence before the House of Commons in 1816: 'Gold is procured in every part of the country; it appears more like an impregnation of the soil than a mine.' His long captivity at Kumasi, where to a certain extent he learned the Oji speech, familiarised him with the native processes; and thus a Frenchman taught Englishmen to work gold in a golden land where they have been domiciled—true fainéants—for nearly three centuries. He came out in the Dries of 1877 with the intention of dredging the Ancobra River where the natives dive for the precious metal. He was working in western Apinto, a province of Wásá, under Kofi Blay, a vassal of King Kwábina Angu, when he was visited (January 1878) by Major-General Wray, B.A., Colonel Lightfoot, and Mr. Hervey, who were curious to see the work. They remained only till the return of the mail-steamer, or about five weeks. The General left with some first-rate sketches; the Colonel caught a fever, which killed him at Madeira; and the Esquire, who bears a name well known in Australia, returned to the Gold Coast for the purpose of writing not unprofitable reports. M. Bonnat was presently informed of the Tákwá Ridge, mines well known for a century at least to Cape Coast Castle, and ever the principal source of the Axim currency. They were still worked in 1875 by the people who drew their stores from Axim. A five-weeks' residence convinced him that they were rich enough to attract capital; he went to Europe, and was successful in raising it. Thus began the Tákwá mines, where, by a kind of irony of Fate, the beginner was buried.
M. Bonnat wisely intended to open operations with wet-working. At Axim I was shown a model flume, made to order after the plans of a M. Boisonnet, or, as he signs himself, 'boisonnet.' He was reported to be a large landed-proprietor who had made a fortune by mining in French Guiana. He proposed for M. Bonnat and himself to secure the monopoly of washing the Protectorate with this flume—a veritable French toy, uselessly complicated, and yet to be used only upon the smallest scale. We must go for our models to California and Australia, not to French Guiana.
The following will be the implements with which the natives of the future must do their work on the Gold Coast:—
The pan begat the cradle, a wooden box on rockers, shaped like the article which gave its name. It measures three feet and a half by eighteen inches, and is provided with a movable hopper and slides. Placed in a sloping position, it is worked to and fro by a perpendicular staff acting as handle, and the grain-gold, a metal seven times heavier than granite, collects where the baby should be. As some flour-gold is here found, the cradle-bottom should be cut with cross-grooves to hold mercury; and the latter must be tempered with sodium or other amalgam.
The cradle begat Long Tom and Broad Tom, the 'tom' proper being the upper box with a grating to keep out the pebbles. 'Long Tom's' body is a wooden trough, from twelve to fourteen feet long by a foot or a foot and a half broad, with ripples, riffles, or cross-bars. There is usually another grating at the lower end to intercept the smaller stones. The machine is fixed in a gently sloping position, at an angle determined by circumstances; the wash-dirt is lifted into the upper end by manual labour; when stiff it must be stirred or shovelled, and a stream of water does the rest. The greater gravity of the gold causes it to be arrested by the riffles. Instead of the bars grooves may be cut and filled with quicksilver. When the sludge is very rich, rough cloths rubbed with mercury, or even sheepskins, the lineal descendants of the Golden Fleece, may be used, 'Broad Tom,' alias the 'Victoria Jenny Lind,' is made about half the length of its long brother: the upper end is only a foot wide, broadening out to three below.
'Tom' begat the sluice, which is of two kinds, natural and artificial. The former is a ditch cut in the floor, with a talus of one to forty or fifty. The bottom, which would soon wear away, is revetted with rough planks and paved with hard stones, weighing ten to twenty pounds, the grain being placed vertically. With a full head of water 400 cubic yards a day can easily be washed. The gold, as usual, gravitates through the chinks to the bottom, and finally is cradled or panned out. It is most efficiently treated when the sluice is long; it demands six times more water than the artificial article, but it wants less manual labour. This last property should recommend it to the Gold Coast. Here, I repeat, machinery must be used as much and manual labour as little as possible.
The artificial or portable box-sluice is a series of troughs each about twelve feet long, like the upper compartment of 'Long Tom.' They are made of half-inch boards, rough from the saw, the lower end being smaller to fit into its prolongation. Each compartment is provided with a loose metal bottom pierced with holes to admit the dust; the true bottom below it has cross-riffles, and above it are bars or gratings to catch the coarser stones. These sluices are mounted on trestles, and the latter are disposed upon a slope determined by the quantity of water: the average fall or grade may be 1 to 50. In Australia four men filling a 'Long Tom,' or raised box-sluice, will remove and wash twenty-four cubic yards of ground per day. When the ore is fine, mercury may be dropped into the upper end of the sluice; and it picks up the particles, 'tailing,' as it goes, before the two metals have run far down. Both stop at the first riffle or resting-place.
The auriferous clays of the Gold Coast are thinly covered with humus, and are not buried, as in Australia, by ten to thirty feet of unproductive top-drift. The whole, therefore, can be run through the sluices before we begin mining the underlying strata. Washing will be easier during the Rains, when the dirt is looser; in the Dries hard and compact stuff must be loosened by the pick and spade or by blasting. There will not be much loss by float-gold, flour-gold, or paint-gold, the latter thus called because it is so fine as to resemble gilding. Spangles and specks are found; but the greater part of the dust is granular, increasing to 'shotty gold.' The natives divide the noble ore into 'dust-gold' and 'mountain-gold.' The latter would consist of nuggets, 'lobs,' or pépites, and of crystals varying in size from a pin's head to a pea. The form is a cube modified to an octahedron and a rhombic dodecahedron. These rich finds are usually the produce of pockets or 'jewellers' shops.' I am not aware if there be any truth in the rule generally accepted: 'The forms of gold are found to differ according to the nature of the underlying rock: if it is slate the grains are cubical; if granite they are flat plates and scales.'