Topaz
(tô-paz')
13th c.; lat. topazus; gr. topazos
Colorless, blue, yellow, brown, or pink aluminum silicate mineral, often found in association with granitic rocks and valued as a gemstone, especially in the brown and pink varieties
Family
Aluminum fluosilicate
Chemical composition
Al2(F,OH)2SiO4
Crystal system
Orthorhombic
Specific gravity
3,53 ±0,04
Refractive index
1,619 - 1,627 ±0,01
Optical character
Biaxial +