Topaz

Topaz is very common gemstone that has been used few centuries in jewelry. Its golden brown to yellow color is classic but it is confused with the less valuable citrine that is sold under the name topaz. The blue topaz that is often confused with aquamarine is not often natural and is produced by irradiating and then heating clear crystals. Topaz is the November Birthstone.

The mineral topaz is a silicate of aluminum and also fluorine with the chemical formula (AlF) 2SiO4. It is orthorhombic and its crystals are mainly prismatic terminated by pyramidal and other faces also, the basal pinacoid often being present. It has an easy and perfect basal cleavage and hence gemstones and other fine specimens must be handled with care to avoid developing cleavage flaws. The fracture is concordat to uneven. Topaz has a hardness of 7, a specific gravity of 3.4-3.5, and a vitreous luster. Pure topaz is transparent but it is usually tinted by impurities; typical topaz is wine and straw-yellow. They can also be white, gray, green, blue, or reddish-yellow also and transparent or translucent. When heated, yellow topaz often becomes reddish-pink.

Topaz is found associated with the more acid rocks of the granite and a rhyolite type and could be found with fluorite and considerate. It may be found in the Ural and Ilmen mountains, Czechoslovakia, Saxony, Norway, Sweden, Japan, Brazil, Mexico, and also in the United States.

The name "topaz" is derived from the Greek "to seek," which was the name of an island in the Red Sea that was quite difficult to find and from which a yellow stone (now believed to be a yellowish olivine) was mined in the ancient times. In the middle Ages the name topaz was used to refer to any yellow gemstone, but now this name is only properly applied to the silicate described above.