mineral

Moonstone

Orthoclase (Potassium Aluminum Silicate, KAlSi3O8) with inclusions of Albite

Mohs hardness: 6.0-6.5; Color: Colorless to white, pale yellow, or peach with a blue/white adularescence; Luster: Vitreous to pearly; Crystal structure: Monoclinic; Cleavage: Perfect in two directions at 90 degrees; Specific gravity: 2.56-2.59

Hardness: 6
Luster: Vitreous to pearly

Identified June 16, 2026More mineral →

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Physical properties

Formation & geological history

Formed in igneous and metamorphic rocks, specifically within pegmatites or hydrothermal veins. The distinct 'glow' (adularescence) is caused by the intergrowth of two different types of feldspar (orthoclase and albite) that separate as the magma cools, creating thin layers that scatter light.

Uses & applications

Primarily used as a gemstone for jewelry (rings, pendants, earrings), as a collector's mineral, and in some metaphysical applications.

Geological facts

The phenomenon of its glow is called adularescence. It is the Florida State Gemstone (commemorating the Moon landing) and is traditionally the birthstone for June. Ancient Romans believed moonstones were formed from frozen moonlight.

Field identification & locations

Identify by looking for a characteristic blue or white 'sheen' that move across the surface as the stone is rotated under a light source. Commonly found in Sri Lanka, India, Myanmar, and Madagascar. In the field, look for cleavage planes and a pearly luster.

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Mineral/Rock

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