topaz

Topaz is a silicate mineral in the aluminum silicate family with the chemical formula Al2SiO4(F,OH)2. It crystallizes in the orthorhombic system and typically forms transparent, prismatic crystals with a vitreous luster. On the Mohs scale it has a hardness of 8, making it a durable gemstone suitable for jewelry. The color range is broad, from colorless and pale yellow to brown, orange, and pink, with blue and green varieties also seen. Natural blue topaz is relatively rare; most blue stones on the market are treated by irradiation and heat. Pink topaz can occur naturally or result from treatment.

Among the best-known gemstone varieties are imperial topaz (golden-orange with a pinkish hue), Swiss blue topaz, and London blue topaz. Mystic Topaz refers to a coated surface that produces a rainbow-like color effect. Clear to lightly colored topaz is often used as an alternative to more expensive stones.

Topaz forms primarily in granitic pegmatites and in hydrothermal environments, and it is found in many parts of the world, including Brazil, Sri Lanka, Nigeria, Russia, Pakistan, and the United States. It is commonly associated with quartz, tourmaline, and micas.

In gemology, topaz is valued for its range of colors and clarity, though its hardness makes it susceptible to scratching and it can be sensitive to rapid temperature changes. It is typically cleaned with warm water and a mild detergent and should be protected from sharp blows. The name topaz likely derives from ancient languages referring to fire or brilliance.

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