Orthoclase
Feldspar
Orthoclase is part of the feldspar mineral family, one of the most abundant mineral families in the world. It is a common constituent in granite used for industrial purposes. For example, "Black Pearl" granite countertops are composed mostly of feldspar. While orthoclase, a potassium-rich feldspar, is better known to collectors, there is one variety that many are familiar with: moonstone, prized for its shimmering adularescence.
General Information
LWUV: transparent yellow: inert to weak reddish orangesemitranslucent white: red
Orthoclase Colors
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Black -
Brown -
Brown -
Brown -
Colorless -
Gray -
Green -
Green -
Orange -
Orange -
Pink -
White -
Yellow -
Yellow -
Yellow
Alternate Names
Adularia, Moonstone, Sunstone
Countries of Origin
Pakistan; Unknown; United States of America; Brazil; Italy; Madagascar; India
Care
Normal Care except for sunstone where ultrasonic cleaners should be avoided.
Optical Phenomena
Orthoclase Moonstone
Orthoclase moonstone is a variety of feldspar that displays an amazing optical phenomenon called adularescence. Internally repeating feldspar layers scatter the light that enters the stone creating a mystical white glow reminiscent of moonbeams. It can be colorless to white, orange, yellow or brown.
Orthoclase Sunstone
Orthoclase sunstone is the aventurescent variety of orthoclase feldspar. Some of the best orthoclase sunstone comes from the Hart’s Range area in Australia. In the gemstone trade this material is called “rainbow lattice sunstone”. This material contains hematite and ilmenite platelets and shows rainbow interference colors. Oregon also produces “Oregon Cinnamon Sunstone” that contains hematite platelets.
