THE BOOK OF DIAMONDS
mass
of the worthless earth, dust and clay, until the water runs clear, and
this washing may be repeated. In this way a pocket full of diamonds may
sometimes but very rarely be found.
The
miners use diving machines, probably movable caissons, in which, a man
can work for several hours on the river bottom. Under cover of one of
these, two men work alternately, it is said, in three-hour shifts,
gathering the cascalho into sacks lowered to them from the surface.
Others dive for the cascalho much the same as the pearl divers dive on
the pearl banks, gathering as much of the gravel as they can during the
submergence. In the shallows, others drag the gravel into the mouths of
sacks with their feet. The diamantiferous material is found not only in
the beds of the streams and rivers, but also in fissures and gullies in
the rocks which band the valleys of the watercourses, as in the other
Brazilian fields. The sands and gravels are gathered from the beds of
the streams in dry seasons, and from fissures and beds in the rocks
during the wet seasons. The richest finds are made usually in pot-holes
in the river beds.
The
tools and methods used in the mining are crude, and some think that
with capital and machinery better results could be obtained, but it is
doubtful if it would be as profitable on the average. Undoubtedly there
are great deposits of diamantiferous material yet unworked, and there
are doubtless rich gravels in the sections already worked which cannot
be reached with the appliances now in use, as for instance the lower
parts of the deposits in
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