Rutilated Quartz & Tourmalinated Quartz |
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 While most varieties of transparent quartz are valued most when they lack inclusions, some varieties are valued chiefly because of inclusions! The most popular of these is known as rutilated quartz. Rutilated quartz is a transparent rock crystal with golden needles of rutile arrayed in patterns inside. Every pattern is different and some are breathtakingly beautiful. The inclusions are sometimes called Venus hair. Less well known is a variety called tourmalinated quartz which, instead of golden rutile, has black or dark green tourmaline crystals. 
Smokey Quartz:
Smoky quartz is a brown transparent quartz that is sometimes used for unusual faceted cuts. This variety was sometimes known as smoky topaz in the past, which is incorrect and misleading, since the mineral variety is quartz, not topaz.
 Tiger's Eye:
Tiger's Eye quartz contains brown iron which produces its golden-yellow color. Cabochon cut stones of this variety show the chatoyancy (small ray of light on the surface) that resembles the feline eye of a tiger. The most important deposit is in South Africa, though Tiger's eye is also found in Western Australia, Burma (Myanmar), India and the U.S. (California).
Chalcedonies:
Quartz that is formed not of one single crystal but finely grained
micro-crystals is known as chalcedony. The variety of chalcedony is even greater than transparent quartz varieties because it includes
crypto-crystalline quartz with patterns as well as a wide range of solid colors. Agates are banded, bloodstone has red spots on a green ground, moss agate has a vegetal pattern.
 Jasper sometimes looks like a landscape painting. Another staple of the jewelry industry is black onyx, chalcedony quartz which owes its even black color to an ancient dyeing process that is still used today. Carnelian, another chalcedony valued in the ancient world, has a vivid brownish orange color and clear translucency that makes it popular for signet rings and seals.
 Chrysoprase, a bright apple green translucent chalcedony, is the most valued. It was a particular favorite of Frederick The Great of Prussia, who loved its bright green color. It can be seen today decorating many buildings in beautiful Prague, including the Chapel of St Wencelas. Chrysoprase is found today mostly in Australia. Unlike most other green stones, which owe their color to chromium or vanadium, chrysoprase derives its color from nickel. Its bright even color and texture lends itself well to beads, cabochons, and carvings.
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