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28 A Book of Precious Stones
and
prairie washings. The river deposits are rolled quartz pebbles, mixed
with or united by a ferruginous clay of which the usual foundation is
talcose clays. Associated minerals include, rutile, hematite,
ilmenite, quartz, kyanite, tourmaline, gold, garnet, and zircon. The
finest stones result from the prairie washings, where the diamonds
occur in a conglomerate of quartz fragments overlaid by earth or sand.
Bagagem is a productive locality, and there a fine stone weighing
247-1/2 carats was found. Abatehe, Minas Geraes, is another important
field. Diamonds are also found at Lencaes, Bahia; along the river
Cacholira, chiefly at Surua and Sinorca, and on the Salobro and other
branches of the Pardo River.
The
world's diamond markets to-day are almost entirely supplied by the
diggings in South Africa, where the discovery of diamonds was so recent
as 1867. Children are accredited with the finding of the diamond in
South Africa. A Boer farmer, Daniel Jacobs, had a farm near the present
town of Barkly West on the Vaal River. On the river's strand were many
glittering and coloured pebbles, the only playthings the Jacobs
children could get; these pebbles included carnelian, agates and many
varieties of
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