178 The Turquoise.
a
copper wheel being employed in cutting it, and the polish obtained by
the use of tripoli and oil. The peridot very closely resembles the
green tourmaline, from which, however, it may be readily distinguished
by its non-electrical properties when heated, and by its softness. The
name chrysolite is derived from χρυσοί, gold, and λίθος, a
stone. Peridot in many oriental languages signifies a gem. The
chrysolite is conjectured to have been the so-called topaz of Pliny,
who, however, confounds it with the chrysoberyl as well as the topaz.
The value both of the chrysolite and peridot is very small ; fine specimens of good size may be bought at from 1s. to 15s. the
carat. A few years ago they were in tolerable demand for jewellery
purposes, when they commanded a much larger price than at present.
THE TURQUOISE.
This
stone, in ancient times called the Türkis or Turkey stone, is found in
reniform or stalactitic masses, never in crystals ; it has a hardness
of 6 in the scale (although specimens vary considerably), and a
specific gravity of 2-6. It possesses a somewhat waxy
lustre, is occasionally translucent, although generally opaque, and has
a smali conchoidal fracture, with a white streak.
Its composition is as follows '—
