Orthoclase is a mineral series in the feldspar group.

Gemological Information for Orthoclase Feldspar

Color: Colorless, White, Green, Orange, Yellow, Brown, Gray and Black
Crystal Structure Monoclinic
Refractive Index: 1.518 to 1.526
Durability: Not Very Durable
Hardness: 6 to 6.5
Family: Feldspar
Similar Stones: Chalcedony and Quartz
Treatments: Blue or Black Coating on Reverse
Country of Origin: Sri Lanka, Myanmar, India

Orthoclase Feldspar Care

Ultrasonic Cleaning: Never
Steam Cleaning: Never
Warm Soapy Water: Safe
Chemical Attack: Hydrofluoric Acid
Light Sensitivity: Stable
Heat Sensitivity: Can Crack or Cleave when Heated


  • Gem Reference Guide, Los Angeles: Gemological Institute of America, 1988. Pp. 103-105.
  • Newman, Harold. An Illustrated Dictionary of Jewelry, New York: Thames and Hudson, 1981. Pp. 224.
  • Schumann, Walter. Gemstones of the World, New York: Sterling Publishing, Co., 1977. Pp. 164.