PRECIOUS STONES. 249
Its specific gravity is 3'95 to 4-29, its hardness is 7-1/4,, its index of refraction for red light is l-77,
and it has the peculiarity of showing absorption hands in the spectrum.
It fuses easily before the blowpipe, and is slightly magnetic.
It
is a widely distributed form of Garnet; the principal localities for
the gem qualities are in the East. In Ceylon it is found in fine
crystals in mica-schist near Trincomali; it also occurs in the gravels
; from this occurrence it is sometimes known as Ceylonese Ruby. The
so-called " Syrian " Garnet was supposed to come from Suriam in Pegu
(Lower Burma), but its occurrence is not authenticated here. The term
refers now rather to Garnet of a violet shade than to material from any
special place.
In
India it is found at the Sanvar mines in Rajputana, near the Godivari
river in gneiss, in Haiderabad, and at Kakoria in Jaipur.
In
Brazil it is found in the Manas Novas district; in Australia a kind
known as Adelaide Ruby is found in the north of South Australia ; in
the United States on the Columbia River; and in Europe in the Ziller
Thai in the Tyrol, in schist.
Spessartite is
of a dark hyacinth-red colour with a specific gravity of 4'0 to 4"3.
Transparent material suitable for gem use has been found at the Mica
mine near Amelia Court House in Virginia, United States.
Andradite, called
also Common Garnet and Black Garnet, includes three varieties sometimes
used as precious stones. In general Andradite occurs in many shades of
yellow, green, brown and grey ; some in black. The specific gravity is
3'83 to 3-90.
The variety Demantoid is found of a grass-green to
