MINING OF GEMS
The
methods employed in the mining of gems depend obviously upon the
occurrence of the latter. If occurring in gravels, or decomposed rock
areas, as is the case with the majority of gems, mining usually takes
the form of open cuts, made either by digging numerous small pits, or
one of extensive dimensions. The separation of the gems from the common
pebbles accompanying them is then performed by some method of washing,
usually hand panning combined with hand picking. Panning depends for
its operation upon the generally high specific gravity of the gem
minerals as compared with those of commoner occurrence, and is thus
similar in principle to gold panning. The utensil most commonly
employed is a shallow pan of wood or metal, from 12 to 18 inches in
diameter, and of a more or less conical shape. On taking up a quantity
of the gem-bearing gravel in this with water, and rinsing the whole
with a circular motion, the lighter minerals fly off and the heavier
concentrate toward the center. After the contents of the pan have in
this manner been considerably reduced, by searching and hand picking
any gems which may have gathered at the center can usually be readily
seen and picked out.
Of
the methods of mining and separating gravels by hand digging and
panning, the procedure of the Cingalese in exploiting the Ceylon gem
gravels may be considered a good illustration. These methods are thus
described by Dr. A. C. Hamlin:
"The
mining operations are generally carried on by the native Cingalese, who
labor in the light of a pastime, and only during intervals of their
agricultural employments. Some few, however, undertake the labor as a
regular business, but they belong to a low and dissipated class, and do
not work systematically or with regularity. Therefore, the gem-mining
of Ceylon cannot be regarded as a fixed and permanent business.
"When
an exploration has been determined upon, a small party of villagers set
out for the promising region provided with the implements of mining
and the means of camping out. The times selected for the operations are
after the heavy rains, which prevail in June and October, and the
floods have subsided. The beds of rivers, or smaller
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