Moonstone
(moon--ston')
11th c; ind-eur root moo; Ger. stein , Slav. stena, Sansk. styayate
A gemstone variety of the mineral potassium feldspar. It has a pale opalescent lustre because of its fine-scale oriented microstructure, showing an effect called adularescence
Color
Transparent to translucent colorless to white
Chemical composition
KAlSi3O8
Crystal system
Monoclinic
Hardness (Mohs scale)
6 - 6,5
Specific gravity
2,56 ±0,01
Refractive index
1,518 - 1,526
Optical character
Biaxial -