Amur.—In
the Amur region the gold-mining industry has been developed
successfully, especially along the Zehya, the Burehya, and the Amgun
rivers, but its progress has been checked by the scantiness of
population. Two thousand men are said to be employed on the rivers Ura
and Oldoi washing the alluvions, which are about seven feet thick. The
placers of the Amur basin, in Trans-Baikalia, are a comparatively
recent discovery. Gold is widely disseminated along the chief affluents
of this river, and the deposits are easily worked.
This
basin is reported to have yielded, up to 1875, a profit of £3,500,000.
The auriferous deposits are estimated by Bogoliubsky to be one
thousand miles long, three hundred and fifty feet wide, and to average
five feet in depth, containing 16^ grains per 3,600 pounds. Only
one-half of the basin is as yet explored.
Placers are found on the islands in the Sea of Japan, in Strelok Bay, and along the shore of the Okhotsk Sea.
Nerchinsk.—The
placers in the Nerchinsk district are generally frozen. Detritus which
yields less than 1 pennyweight per 1,800 pounds has been found
unprofitable to work.
Brazil.—In
1543 gold was known to exist in Brazil (Walsh, vol. ii. p. 101),
deposited in the beds of streams. The Indians at that period are said
to have used it to make fish-hooks. Humboldt (" New Spain," vol. iii.
p. 401) says that gold-placers were first discovered in 1577. The
greatest prosperity of the gold-washings was in the middle of the
eighteenth century.
The
precious metal was first found in the Riberao, a tributary of the Rio
das Mortes, or River of Death. This name commemorates a bloody
encounter which took place between the gold-hunters, who, it is said,
met and " set upon each other like famished tigers, impelled by the auri sacra fames." * •
In the vicinity of the Riberao there is abundant evi-
* Walsh, lt Travels in Brazil," vol. i. p. 104.
