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Page:Popular Science Monthly Volume 21.djvu/632

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THE POPULAR SCIENCE MONTHLY.

through the soil, accompanied only by a few bits of quartz. According to the popular expression, the crystals of the precious stone could be picked out of the roots of the grass when it was pulled up. A diamond of twenty-eight carats was found on the surface of the ground. At some distance from this spot, I have myself seen, on the summit of the ridge between the valleys of the Jequitinhonha and the Rio das Velhas, diamonds in ground-cracks some inches deep, with no other companions than enormous crystals of quartz. Cavities in the rock a few metres away did not contain a trace of diamonds, although they bore identical crystals of quartz. The old miners ascribed the disposition of the minerals they sought in regular veins to the intervention of good genii. It seems as if, at Diamantina, a wicked fairy must have sown the diamonds on the ground according to its caprices; and never were caprices more whimsical and varied. . The diamond there forms only an insignificant part of the gravels, and is in most uncertain proportions.

The work of washing the diamonds is done wholly by hand. In the first operation, the sands are placed, in portions of two hundred to two hundred and fifty pounds, in a kind of hod or rectangular trough, only three sides of which are inclosed. The hods are arranged by twos, fours, or sixes, by the side of a trough of water about a foot and a half deep, so that their bottoms shall be slightly inclined toward it. A workman, standing in the trough before each hod, dashes water upon the sand in it. The clay and the very fine sands are carried away, and the first separation is made. The larger pieces remaining in the top of the sand are picked away; the diamond is to be found in the two upper thirds of the mass that is left, the lower part being nearly sterile. The washing is afterward finished in bowls a little deeper and a little more conical than those used by the gold-washers. The washer puts the sand in the bowl and fills it with water; then by whirling the bowl and shaking it up and down while the sand is floating around in it, and being careful to stir it from time to time with his hand, he determines a classification in the order of density. This work is easy if he is washing gold; for that metal is heavier than the substances with which it occurs, and always goes to the bottom.

The diamond, however, having a density about three and a half times greater than that of water, and more considerable than that of quartz and tourmaline, but less than that of the oxides of iron and titanium, its constant companions, settles in the middle layers. The washer, after several rinsings, removes the upper particles, hardly looking at them, and, when he has reached a certain level, which his skill recognizes at once, tips his bowl slightly, so as to let the water run off in a thin film, and, perceiving the glittering crystals of the diamond, picks them out with his fingers. The vigilance of the overseers must be redoubled at this stage, particularly when slaves are employed; for I know of nothing equal to the skill of the slaves in find-