364 THE RUBY MINES OF UPPER BURMA
Mr.
Brown has shown that the geological formation consists of recent
deposits of hill wash and alluvium and old crystalline limestones,
schists, pegmatite, and other metamorphic rocks. In order to explain
the relationship which exists between these formations and the rubies,
it will be convenient to describe the various systems of mining, by
which the mode of occurrence will be made apparent. The mines, as
worked by the natives, may be divided into four classes, as follows :
I. Twinlones, or pits sunk in the alluvium of the valleys.
II. Mewdwins, or open cuttings in the hill-wash over which water is led.
III. Loodwins, or workings in caves and fissures.
IV. Quarries in a bed of coarse calcspar in the limestone,
which appears to be the true original matrix of the gems.
The
Twinlones are square pits which are sunk in the alluvium of the valleys
down to the gem-bearing gravels, which occur at varying depths. These
pits have to be timbered to support the sides and, as far as possible,
exclude water, which, however, finds access, and the first operation,
every day, is to bale out the water which has accumulated during the
night. The gravel is hoisted out in baskets by means of balance poles
similar to those which are used in India for raising water from wells.
The gravel is then washed in shallow baskets made of closely-woven
bamboo, and the rubies, as they are picked out, are placed in a bamboo
tube full of water and are sorted at the close of the day's work. The
larger pits are generally cleared out in about ten days and the smaller
in half that time ; when working in one is finished, the timber is
removed and another pit is started.
Mewdwins.—-These
are open cuttings on the slopes of the hills to which water is
conducted, often from a considerable distance, and discharged with as
great a head as possible on the ruby clay and sand, which is shovelled
under it by the miners. The lighter portions are carried down by the
stream, the boulders removed by hand, and the residue placed in the
sluice and washed, where it is caught by riffles, from whence it is
removed and washed in baskets as in the preceding process. The
circumstances appear to be such as would suit a more scientific
application of hydraulic methods than-are known to the natives.
Loodwins.—These
are natural caves and fissures in the limestone rock, in the floors and
crevices of which the rubies have accumulated in consequence of the
solution by water of the limestone matrix. In the ordinary sense of the
term these are not mines, i. e. the miners do not excavate the rock,
but merely scramble through the natural passages and
