Semi-Precious Stones 193
dish
brown to brownish black; hardness, 7.5. The transparent kinds when cut
resemble garnets. Because of their resemblance to a cross, the twinned
forms are used to quite an extent as ornaments and charms; there is a
tradition that they fell from heaven.
TITANITE,
or sphene, possesses an adamantine lustre, as does the diamond, and
gems cut from this mineral are quite effective, but they lack the
desired depth of colour and hardness to confer upon them a higher rank
in the company of gems. The colour range of titanite is considerable,
and transparent pieces, according to their colour, when cut, resemble
topaz, garnet, chrysolite, and other stones. Sphene crystallises in
the monoclinic system, the crystals frequently having the shape of a
wedge; the name sphene is taken from the Greek sphen, meaning a wedge.
ZIRCON is alphabetically the omega of
the semi-precious stones occasionally used, but, as it is probably used
much more than any other mineral in this category, it is almost
entitled to a chapter of its own. High specific gravity and an
adamantine lustre are two marked characteristics of this mineral.
Zircons are called ' Matura diamonds," because of their abundance
