116 The Chrysoberyl, Cymophane, etc.
or brownish-yellow colour, occasionally white ; some varieties showing
a reddish tint by transmitted light. Some specimens possess an
opalescence, and these are generally cut en cabochon, when they are called chrysolite, or chrysoberyl cat's-eye, or cymophanes.
belongs to the trimetric or rhombic system of crystallization, and
possesses a vitreous lustre ; it varies from being perfectly
transparent to nearly opaque ; its cleavage is not very
perfect, and it breaks with a conchoidal fracture rather uneven ; its
specific gravity varies from 3'68o to 3.754, and its hardness is
numbered in the scale as 8-5, being scratched by the
sapphire, ruby, etc., and scratching quartz easily. It possesses double
refraction to a high degree, and acquires positive electricity by
friction, retaining it for several hours.
is infusible before the blowpipe alone, but melts with difficulty to a
clear glass with borax or salt of phosphorus. It is not affected by
Its chemical composition is—