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The ABC's of TOPAZTopaz, the birthstone for those born in the month of November, is an aluminum silicate mineral. Commonly colorless or some shade of yellow, the stone is transparent with a vitreous luster. Topaz crystals occur in highly acidic igneous rocks and in metamorphic rocks.
Crystals occur in generally in pegmatite dykes, formed when hot magma risies from the earth's mantle but fails to erupt as a volcano. The cooled magma forms granite veins in the earth's crust, and the topaz crystals are imbedded in these veins. Brown, yellow, orange, sherry, red and pink topaz is found primarily in Brazil and Sri Lanka. Pink topaz is found in Pakistan and Russia. Some topaz is also mined in the United States, in the Rocky Mountains. Today we also have blue topaz, which has a pale to medium blue color created by irradiation. Pale topaz which is enhanced to become blue is found in Brazil, Sri Lanka, Nigeria, and China. In early 1998, a new type of enhanced topaz made its appearance, the surface-enhanced topaz, with colors described as blue to greenish-blue or emerald green. The natural blues and greens in topaz are usually too pale to be very vivid.
The much-sought Imperial Topaz, which runs from bright orange to a warm red in color, is found in only one location in the world: Ouro Preto in Brazil. The world's entire supply of Imperial Topaz is mined from two mines, the Vermelhao Mine and the Capao Mine, in a 60 square mile area. Some experts expect the Imperial Topaz sources to be completely exhausted by the end of the century.
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