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Sec. II, Ch. 5: The Brazilian Diamond

Sec. II, Ch. 5: The Brazilian Diamond Page of 366 Sec. II, Ch. 5: The Brazilian Diamond Text size:minus plus Restore normal size   Mail page  Print this page
Brazilian Diamonds.
109
The Diamond washings in the neighbourhood of Diamantina are performed either in old river gravels or in the beds of rivers, in whose bottoms continuous pot-holes or canons are found, filled with the Diamond-bearing gravel. The courses of the rivers are turned by means of temporary dams or wooden sluices, and the Diamond-bearing gravel hollowed out. The principal minerals associated with the Diamond are anatase, rutile, brookite, specular iron, martite, topaz, tourmaline, and native gold.
At Sâo Joâo da Chapada, about 12 miles to the west of Diamantina, the Diamond occurs embedded in clay, or barro, under the conditions which have been described by Prof. O. A. Derby. The clay contains grains of quartz and microscopic tourmalines, but the rock from which it has been derived by decomposition has not been definitely detected.
About 100 miles north of Diamantina, on the Corrego dos Bois, near Grâo Mogol, the Diamond has been found in a solid conglomerate rock named by the miners " Pigeons' Eggs." This was formerly regarded as the Itacolumite, but has been identified with the upper series, overlying the true Itacolumite group. In 1839 about 2,000 people flocked here to work.
Diamonds occur in the valley of the River Tibagy (in the Province of Parana, in Southern Brazil) and in its tributaries the Yapo and Pitangru. The stones are found not only in the sands of the river, especially in pot-holes, but in old beds of gravel at some distance above the present level of the river, where " dry washings " have been established. The story told of the discovery of Diamonds here is, that a labourer, living close to Tibagy, produced a tiny bamboo stem, the open end of which was stuffed with a twisted leaf of milho; on extracting this, some small,
Sec. II, Ch. 5: The Brazilian Diamond Page of 366 Sec. II, Ch. 5: The Brazilian Diamond
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