A Hand-book of Precious StonesRothschild, Meyer D.
Science
A Hand-book of Precious Stones
Rothschild, Meyer D.
Precious stones
The oyster itself is small for the size of the shell.
This specimen is found on the coast of Ceylon, Persian Gulf, Japanese,
Mexican and California coasts, the western shores of South America,
Brazil, West Indian Islands, Panama, Sooloo Archipelago, and the
northeast and northwestern coast of Australia.
The fresh-water or unio margaritifera is an even, egg-shaped mussel
found in brooks, rivers, and lakes in temperate zones in nearly all
parts of the world.
Some fine river pearls have been found in the United States, but most
of the American pearls are of a button or elongated shape, or are
baroques or fancy-shaped.
In China many people engage in the business of making small pellets of
clay or metal images, which in the month of May are introduced into the
river mussels (mytilus cygneus).
The mussels are replanted, and in November they are taken up again.
Some of the oysters die, but most of them are found to have been
actively at work covering the little pellets or metal figures with
nacre, and while no strictly first-class pearls are formed in this way,
many curious little pearl figures or gods are made and sold to the
curious or devout.
Pink or conch pearls are found in the Gulf of California and coasts
of Mexico, Bahama Islands, West Indian Islands, and in some rivers in
South America.
They seldom occur in regular shapes, and although they are termed pink
pearls, they range in color from red to pale yellow, and are often
found of a china-white color.
The pink pearl displays a wavy appearance and a peculiar sheen,
something like watered silk. As the pink pearl is seldom found
perfectly round and of a good color, such a specimen is very valuable.
CHRYSOLITE.
The chrysolite, peridot, and olivine differ in color, but are
practically of the same composition.
The chrysolite proper is of a pale greenish-yellow color, the peridot a
deep olive-green, and the olivine of a yellowish or light olive-green
color; these stones also shade into brown. They crystallize on the
rhombic system, are transparent to translucent, 6.5 to 7. in the scale
of hardness, and 3.3 to 3.5 in specific gravity.
The cleavage is distinct, fracture conchoidal, refraction double, and
lustre vitreous, and in the olivines somewhat greasy.
These stones are easily affected by sulphuric acid, but are infusible
before the blow-pipe, excepting some kinds containing much iron.
With borax, they melt to a pale-green transparent glass.
Chrysolites are composed of silica, magnesia, and oxide of iron.
Perfectly crystallized chrysolites are brought from Constantinople, but
the exact locality where they are found is unknown.
Less distinct specimens occur at Vesuvius, Mexico, the isle of Bourbon,
Auvergne, Egypt, Natolia, Brazil, Germany, Pegu, Ceylon, Switzerland,
and North America.
Peridots are distinguished by being the only precious stones that have
literally dropped from heaven, as they have been found in meteorites.
Public-domain text, read in full here on John Shaqi.
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