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Moonstone (gemstone)

Moonstone

General
Category	orthoclase feldspar^[1]
Chemical formula	KAlSi₃O₈
Identification
Molecular Weight	277.83479576
Color	Can be numerous colors, including grey, white, pink, green and brown, but the most valuable are deep blue.
Crystal system	Monoclinic
Mohs Scale hardness	6 - 6.5
Refractive index	1.52 - 1.53 to 1.53 - 1.54
Optical Properties	Biaxial Negative
Dispersion	0.008
Specific gravity	2.55 - 2.58

Moonstone is typically a potassium aluminium silicate, with the chemical formula KAlSi₃O₈ ^[1]

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The most common moonstone is of the mineral Adularia. The Plagioclase Feldspar Oligoclase also produces moonstone specimens. The sheen is caused by light reflecting internally in the moonstone from layer inclusions of different Feldspars.

References

^ ^a ^b Moonstone Gemstone Information.

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