Moonstone Chemical composition: Moonstone is a variety of the feldspar-group mineral orthoclase. During formation, orthoclase and albite separate into alternating layers. When light falls between these thin layers it is scattered producing the phenomenon called adularescence. Adularescence is the light that appears to billow across a gem. Other feldspar minerals can also show adularescence including labradorite and sanidine.

  • Mineral: Feldspar.
  • Chemistry: KAlSi3O8
  • Color: Colorless to White, Gray, Green, Peach, Brown.
  • Refractive index: 1.518 to 1.526.
  • Birefringence: 0.05 to 0.008.
  • Specific gravity: 2.58.
  • Mohs Hardness: 6.0 to 6.5.