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Agate
A variety of
chalcedony. It has a pattern of banding which occurs due to chemical admixtures
of hematite, limonite and other minerals. Examples: Botswana agate, leopard agate,
moss agate.
Amazonite
An orthoclase
of the microcline crystalline form, composed of potassium aluminum silicate. Fine
stones come from Virginia, Colorado, and Russia.
Amethyst
Amethyst is the purple variety of quartz and is a popular gemstone. If it were not for its widespread availability, amethyst would be very expensive. Its color is unparalleled, and even other, more expensive purple gemstones are often compared to its color and beauty. Although it must always be purple to be amethyst, it can have a wide range of purple shades.
Apatite
A brightly colored phosphate-based primary mineral that forms six-sided crystals, often confused with aquamarine, olivine and fluorite.
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