Named in honor of Czar Alexander II of Russia, alexandrite is actually
a very special variety of the mineral chrysoberyl. It exhibits an exotic and
highly prized optical property known as color change. When held in daylight,
it appears greenish, but when held under the warm lights of candles or
incandescent bulbs, it appears reddish. Even more exotic is the doubly
special cat’s-eye alexandrite. This variety of chrysoberyl exhibits both
color change, and a special property known as chatoyancy. The most well-known
source of alexandrite was Russia (Urals); however these deposits have played
out. Notable sources now include Brazil, India, Sri Lanka, and Tanzania
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alloy
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An alloy is a mixture of two or more elements in solid solution in
which the major component is a metal. Most pure metals are either too soft,
brittle or chemically reactive for practical use. Combining different ratios
of metals as alloys modifies the properties of pure metals to produce
desirable characteristics. The aim of making alloys is generally to make them
less brittle, harder, resistant to corrosion, or have a more desirable color
and luster.
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almandite (almandine garnet)
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Almandite is a member of the garnet group of gemstones. It is one of
six species recognized by gemologists. The dominant hue is red, but the
overall color may be modified by a little violet. Chemically it is an
iron-aluminum silicate, but is rarely pure in nature. Almandite is very
popular in jewelry since it is hard (7.5) and durable. Important sources
include Brazil, India, Madagascar, Sri Lanka, and the USA.
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amber
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Amber is the
generic name applied to various types of hardened, fossilized resins. It is
one of the oldest organic gem materials known to man. Scientists often refer
to amber as succinite or retinite. Many variety names are found throughout
the world (rumenite, simetite, burmite, etc.). There is no clearly defined
consensus on what constitutes amber versus copal (baby amber), since
scientists are still debating the relevance of chemistry, age, and other
factors. Some of the oldest amber has been dated back to the Carboniferous
period – nearly 320 million years ago. This makes even Baltic amber
(approximately 30 million years old) young by comparison. Amber is extremely
popular in jewelry, but is also prized by collectors for the variety of
plants, animals and insects that are often found within. Sources of amber are
varied, but include China, Canada, the Dominican Republic, Italy, Myanmar,
Rumania, the USA and many countries bordering the Baltic Sea.
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