Tuesday, November 30, 2010
Wednesday, November 3, 2010
NOVEMBER BIRTH STONE
TOPAZ(THE MINERAL TOPAZ)
Topaz is a common gemstone that has been used for centuries in jewelry. Its golden brown to yellow color is classic but is confused with the less valuable citrine, which is sold under the name topaz. The blue topaz that is often confused with aquamarine is rarely natural and is produced by irradiating and then heating clear crystals. Topaz is the November Birthstone
The structure of Topaz is controlled by a chain like structure of connected irregular octahedrons. These octahedrons have an aluminum in the middle surrounded by four oxygens. Above and below the aluminum are the hydroxide or fluoride ions. The chains of octahedrons are held together by individual silicate tetrahedrons but it is the octahedron chains that give topaz its crystalline shape.
Topaz is the hardest silicate mineral and one of the hardest minerals in nature.
Topaz crystals can reach the incredible size of several hundred pounds. Topaz can make very attractive mineral specimens due to their high luster, nice colors and well formed and multifaceted crystals.
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