A Hand-book of Precious StonesRothschild, Meyer D.
Science
A Hand-book of Precious Stones
Rothschild, Meyer D.
Precious stones
The Oriental chrysolite of commerce is true chrysoberyl, and is harder
and heavier than chrysolite, and the stone called Ceylon chrysolite is
a greenish-yellow tourmaline, which is easily distinguished, as it is
also harder while considerably lighter than the chrysolite.
The green garnet is of a pronounced green color, and is harder and
heavier than the olivine or chrysolite. Although suitable for mounting
in brooches and other ornaments, these stones are not sufficiently hard
for the rough usage as ring-stones.
GARNET.
Almandine, almandite, Syrian garnet, essonite, cinnamon-stone, pyrope,
Bohemian garnet, vermeille, Cape garnet, Cape ruby, Arizona ruby,
American ruby, carbuncle, uwarowite, demantoide, grossularite, and
Bobrowska garnet are some of the scientific and commercial names for
different species and colors of the garnet group.
The crystallization of the garnet is isometric, refraction single,
specific gravity 3.15 to 4.3, hardness 5 to 8, lustre vitreous,
fracture uneven, colors red, violet, brown, yellow, green, and white,
and the various shadings of these colors.
Most varieties fuse easily to a brown or black glass; the uwarowite
fuses with borax to a clear chrome-green glass.
Syrian, almandine, almandite, and carbuncle are different names for the
iron-alumina garnet.
In colors, these stones shade from deep-red to violet and brownish-red,
and are composed of:
Silica 36.01
Alumina 20.06
Protoxide of iron 43.03
The specific gravity is 4. to 4.2, and hardness 7.5.
This garnet, sometimes called the precious garnet, is found in Ceylon,
Pegu, Brazil, Greenland, Hindustan, Bohemia, Tyrol, Œtzthal, Carinthia,
Styria, Switzerland, Ariolo, Canaria, Maggia, Hungary, Sweden, Norway,
Scotland, Spain, and the United States.
Grossularite, or lime-alumina garnet, is known in commerce as essonite,
or cinnamon-stone. The color is yellow, of various shades; specific
gravity 3.5 to 3.65, and hardness 6.5.
These stones are sometimes sold for jacinths, but they are softer than
the jacinth, and melt easily before the blow-pipe. Essonites come
principally from Ceylon, but are also found in other places.
Pyrope or Bohemian garnet is the magnesia-alumina variety, and is of
a uniform dark blood-red color. This stone is found in Bohemia, and
although quantities of small pieces are found, large specimens are
rare, and a piece that will cut into a four- or five-carat stone is
seldom met with and commands a high price.
These garnets are found at Stiefelburg by Meronitz, Triblitz,
Podsedlitz, and Neupaka.
The pyrope turns black under the blow-pipe, then red again, and melts
with difficulty into a black glass. With borax it melts to an
emerald-green glass. The specific gravity of this garnet is 3.69 to
3.78, and hardness 7.5.
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