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PRECIOUS STONES
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and
of a vitreous lustre. When heated on the borax bead it gives an equally
beautiful green, which is. however, rather more inclined to chrome than
emerald. This is an extremely rare stone in fine colour, though cloudy
and imperfect specimens are often met with, but seldom are large stones
found without flaws and of the pure colour. which rivals that of the
emerald in beauty.
The fourth variety (D) is the lime-alumina garnet, its formula being—
the
others, it has a number of sub-varieties, the chief being the "cinnamon
stone," which is one of great beauty and value when perfect. This stone
is almost always transparent when pure, which property is usually taken
as one of the tests of its value, for the slightest admixture or
presence of other substances cloud it, probably to opacity, in
accordance with the quantity of impurity existent. This variety is
composed of the oxides of aluminium and silicon with lime. In colour it
ranges from a beautiful yellowish-orange deepening towards the red to a
pure and beautiful 'red.
"
Romanzovite" is another beautiful variety, the colour of which ranges
through browns to black. Another important variety is the " succinite,"
which gets up well and is a favourite with jewellers because of its
beautiful, amber-like colour, without possessing any of the drawbacks
of amber.
(E) The magnesia-alumina garnet —
—is somewhat rare, the most frequently
found
being of a strong crimson colour and transparent. This variety is
called " pyrope," the deeper and richer tints being designated "
carbuncle," from the Latin car-
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