Topaz

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Topaz
Chemical name	Aluminum silicate fluoride hydroxide
Chemical formula	Al2SiO4(F, OH)3
Identification
Colors	Colorless, white, pale blue, light green, yellow, yellowish brown, or red
Crystal habit	Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline).
Crystal system	Orthorhombic
Cleavage	Perfect (001)
Fracture	Irregular/Uneven, Sub-Conchoidal
Hardness	8
Name origin	Named after Topasos Island in the Red Sea. In antique times, the name was probably used for the gemstone that is now known as peridot.
Specific gravity	3.5 - 3.6, Average = 3.55
Streak	White

Topaz is one of the hardest minerals rating an 8 on the Mohs hardness scale. Chemically, topaz is Aluminum silicate fluoride hydroxide Al₂SiO₄(F, OH)₃ and is classified as a silicate. It is commonly used as a gemstone and its crystals can grow to a very large size. Topaz is commonly a shade of yellow or orange, but may also be colorless and is found in the blue and green ranges. Topaz is the birthstone for November.

Gallery[edit]

• 

  Topaz sample

External links[edit]

• Amethyst Galleries
• Mindat.org
• Webmineral