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 pepites,
and of crystals varying in size from a pin's head to a pea.
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