Smoky quartz
(smo-kee'-kwôrtz)
17th c.; ger. med. quarz; slav. quarc; ind-eur smeug(h)
Transparent or semitransparent light brown to nearly black variety of quartz, used as a gemstone, also called cairngorm
Color
Smoky yellow to smoky brown
Chemical composition
SiO2
Specific gravity
2,66 ±0,01
Refractive index
1,544 - 1,553
Optical character
Uniaxial +