Birds and Nature Vol. 11 No. 4 [April 1902]: Illustrated by Color PhotographyVarious
History
Birds and Nature Vol. 11 No. 4 [April 1902]: Illustrated by Color Photography
Various
Birds -- Periodicals; Natural history -- Periodicals
Two varieties of garnet, almandite and pyrope, may exhibit the dark
blood-red color especially ascribed to garnet. Almandite or almandine
garnet derives its name from Alabanda, a city of Asia Minor, in the
ancient district of Caria, whence garnet was first brought to the
Romans. The finest almandite for a long time came from near the city of
Sirian, in the old province of Pegu, Lower Burmah. While this was the
center of supply, it is not known just where the garnets were obtained.
Such garnets are still known as “Sirian” garnets. Their color tends
toward the violet of the ruby and gives them a high value. There are
several localities in Northern India where almandite is mined on a large
scale, and the stone is much used in Indian jewelry. Some of these
localities are Condapilly, Sarwar and Cacoria. Almandite is also found
in Brazil, in Australia, in several localities in the Alps, and in the
United States. Stones from all these regions are found suitable for
cutting, the only qualifications needed being sufficient size and
transparency and good color. The almandite of Alaska shown in the
accompanying plate occurs in great quantities near the mouth of the
Stickeen river, but has not been extensively cut on account of its being
too opaque. Almandite usually occurs in metamorphic rocks, such as
gneisses or mica schists; also in granite. It is also found in many gem
gravels. From the ruby it can be distinguished, as can all varieties of
garnet, by its lower hardness and single refraction of light. In
artificial light, too, it borrows a yellow tint, rendering it less
pleasing, while the color of ruby grows more intense.
Pyrope, the magnesian variety of garnet, does not differ much in color
from almandite. Both are dark red, but while almandite tends toward a
violet tone, pyrope shades toward yellow. Pyrope is lighter than
almandite, the specific gravity being 3.7 to 3.8, while that of
almandite is 4.1 to 4.3. It is also less easily fusible. It rarely
occurs in crystals, and where found in place is always associated with
the magnesium-bearing rocks, peridotite or serpentine.
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