150

MINERAL RESOURCES.

knowledge often misapply the names, In many cases tests
of hardness, specific gravity, and optical properties are
necessary for an accurate determination,
Of these gems, moonstone is the only onealmost exclusively
dug from the solid rock. It is a clear variety of orthoclase
felspar, and. occurs in large Porphyritic erystals in certain
quartz-felspar rocks and pegmatites. It is especially quarried
in the Dumbara district of the Central Province.

A MOONSTONE PIT.

The silvery sheen is brobably due to incipient decomposition,
 minute flakes of kaolin being arranged in definite
planes within the crystal. The best varieties are those in
which the silvery sheen haga strong blue colour. The large
quantity of the stone which can be obtained prevents its
commanding a very high price; from Rs. 75 to Rs. 100 is the
very highest price which the largest and best stones would
fetch.
Garnetsare likewise obtained in stfu, though occurring also
in the gravels. Garnets of small size but brilliant colour are
exceedingly abundant in many of the crystalline rocks;
occasionally these are large enough and good enough for use
as gems, and are then usually obtained by picking out from
partially decomposed portions of the rock. Cinnamon stone