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CHAPTER XXV.
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OBSIDIAN.
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EOLOGISTS
apply this name to a volcanic glass or fused lava, and at first sight
it may seem strange that such a substance should find a description in
a work on Precious Stones. Obsidian was, however, used by the Ancients
as an ornamental stone, and it is still occasionally cut and polished.
It is generally of bottle-green colour, and when cut looks somewhat
like a Peridot or a green Tourmaline. The great objection to the stone
is its softness, which is rather less than that of Felspar. A brown
streaked American variety is cut and polished under the name of Mahogany Obsidian. A
Siberian variety, with a pleasing silvery sheen, is occasionally used
in the manufacture of snuff-boxes and other ornamental articles.
Curious globular masses of Obsidian, known from a Siberian locality as Marekanite, sometimes explode, when struck, like Ruperts'drops. "Obsidian bombs" are occasionally found in Western Australia, and elsewhere.
OBSIDIAN.
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