panied
with dolomite and encrusting and included in gneiss. The best
specimens of it were of a pure snow-white, earthy texture, rather
harsh to the touch, destitute of smell when breathed on, and not
adhesive. A specimen of it, examined by Dr. Davy, contained 86
carbonate of magnesia, 5 water, 9 silica, with some slight traces of
carbonate of lime.
This
mineral is perhaps co-temporary with the rock in which it occurs, and
not deposited subsequently from water. It has long been used by the
natives of the adjoining country in whitewashing their temples. Talc is
very rare in Ceylon. It has been met with at Dumbara in a nitre cave,
where, with calcspar, felspar and quartz, it entered into the
composition of a highly crystalline rock.
Calcspar,
anhydrous gypsum, and calcsinter are the only pure calcareous minerals
to be found in Ceylon. The two former, well crystallised, have been met
with at Dumbara nitre cave. They occur in the compound rock just
alluded to in reference to talc. Calcsinter is not uncommon; encrusting
rocks of dolomite and gneiss, it abounds in Matale, and is plentiful in
Lower Uva and in many places in the vicinity of dolomite rock, from
which in all probability it is derived.
There
are two kinds of the inflammable class of minerals that occur in
Ceylon, graphite and sulphur. Graphite in minute scales is very
commonly disseminated through gneiss, and it occasionally occurs
imbedded in this rock in small masses. In the latter form, it is found
to some extent in parts of Upper Saffragam, and might probably be found
in sufficient quantity to be collected and exported profitably. Sulphur
is extremely rare in Ceylon, indeed its very existence is not
indisputably proved. A specimen of this mineral was some time ago
picked up in Dumbara, which contained a large portion of sulphate, a
small portion of sulphate of iron, and slight traces of alum. The stone
itself was composed chiefly of quartz, felspar and oxide of iron, and
of some grey crystalline grains. Had the specimen been broken from a
rock, little room for doubt would have remained, but even as the case
stood, it appeared more likely to be native sulphur than an artificial
accidental impregnation, for which indeed it would be almost
impossible tu account. The mineral productions occurring in the
dolomite rock are of two kinds, those peculiar to it and hitherto found
in no other rock in Ceylon, and those common to it and to granitic
rock. Belonging to the latter, the following minerals may be enumerated
:—Iron pyrites, mica, white clay, probably derived from the
decomposition of felspar and graphite. With the exception of mica, none
of these minerals are common or abundant in dolomite. The mica is
generally of a light brown or straw-colour, translucent and
crystallised in small six-sided prisms. The minerals peculiar to
dolomite are three in number, Ceylanite, apatite and a bright yellow
mineral, perhaps a variety of cinnamon-stone. Ceylanite is pretty
abundant in this rock, and very generally disseminated through it. It
occurs crystallized and amorphous, and exhibits a variety of colours,
as bright azure-blue, resembling the blue sapphire, violet, pink-red,
grey and white. Its crystals are generally very small. The fine
sapphire blue Ceylanite is almost confined to one locality. Of the
pink-red, some good specimens have been met with from a vein of
dolomite in Saffragam, on the banks of a stream that flows into the
Kalu-ganga. Ceylanite of the other colours is common particularly in
the dolomite rock near Kandy and Badulla, where it generally occurs
amorphous, or very indistinctly crystallised. Apitite, of a bright
sapphire-blue colour, is frequently to be seen in dolomite,
disseminated in very minute particles. It occurs in one place well
crystallised, in six-sided prisms in a few places. The bright yellow
mineral, perhaps, a variety of the cinnamon-stone, which it resembles
in its general properties, and has never been seen crystallished, is
not uncommon in dolomite in the vicinity of Kandy. This result is
difficult to ascertain from the small particles in which it is found.
Though, then, the number of minerals hitherto found in dolomite rock is
