Natural Moonstone

Moonstone is the most well known variety of orthoclase feldspar. It characteristically exhibits a milky floating blue light known as adularescence or the schiller effect. This lovely sheen is due to a combination of orthoclase and albite arranged in layers. Light reflected from the layers if they are not too thick is responsible for the unusual optical properties.

Moonstone Profile

Color information:	white, blueish white.
Refractive Index:	1.518 – 1.526
Chemical Composition:	KalSI3O8
Hardness:	6 – 6.50
Density:	2.55 – 2.57
Crystal Group:	Monoclinic
Ocurrence:	Sri Lanka, India, Madagascar, Burma, Tanzania, U.S.A.
Sign of the Zodiac:	N/A
Month of the year:	N/A

Moonstone is usually fashioned en cabochon with the blue colors commanding higher prices. A new kind of moonstone has also been recently discovered in Tanzania. Potassium-feldspar (K-feldspar) alcali feldspar, or moonstone with weak asterism, the stones exhibit cat's eyes with a weaker ray perpendicular to the eye producing a four ray star in some specimens. We call it "sunstar".

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