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with
granite or other igneous intrusions, piercing.the older and more
metamorphosed crystalline schists or richly concentrated in pegmatite
off-shoots.
Along
with the sapphire, some pale rubies and semiprecious gems as
aquamarine, rubicelle, green tourmaline quartz, felspar and serpentine
occur. Of the latter the most important is the aquamarine of Daso.
The
Soomjam area was discovered in 1881-1882, and also visited by Mallet in
1882. The mines produced well during the period 1882-1887, followed by
a lull and since 1926 fresh attempts were made. Large quantities of
corundum sapphire have been obtained from a central part of the New
Mines area. The corundum is patchily coloured, varying from pale to
azure and deep blue. The matrix is a small patch of white kaolin or
china clay which is tough, and passes down to a pegmatite containing
felspar, and the sapphire is embedded in it. The pegmatite also
contains tourmaline, garnet, beryl (aquamarine) and corundum. The
pegmatite is considered to form numerous lenticles arranged in series
or rows. In the New Mines, these lenticles of pegmatite have a base of
actinolite and tremolite, which are again in turn found to be
distributed in crystalline limestone.
In
the New Mines, the sapphires are distributed as thick as plums in a
pudding, in small lenticles of the kaolinized pegmatite which are
either enclosed or are intrusives in the tremolite-actinolite rock, the
latter being probably the local modifications of the crystalline
limestone. The corundum sapphire rocks are supposed to have a more
extended distribution than hitherto known. Some placer deposits are
also supposed to exist.
The
stones vary in colour from light to deep sky blue. The greater number
of the stones are of a deep and lively blue, which shows up well in
artificial light. The Kashmir stones are also very popular and command
very high prices.
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