mineral

Moonstone

Orthoclase (Potassium Aluminum Silicate), Formula: (K,Na)AlSi3O8

Hardness: 6.0–6.5 Mohs. Color: White to colorless with a blue or white schiller (adularescence). Luster: Vitreous to Pearly. Crystal structure: Monoclinic. Cleavage: Perfect in two directions. Specific gravity: 2.56–2.59.

Hardness: 6
Luster: Vitreous to Pearly

Identified March 24, 2026More mineral →

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Physical properties

Formation & geological history

Formed in plutonic and metamorphic rocks. The characteristic 'glow' (adularescence) is caused by the intergrowth of two types of feldspar (orthoclase and albite) that separate as the mineral cools, creating layers that scatter light.

Uses & applications

Primarily used in jewelry as cabochons (as seen in the provided image). Frequently used in rings, pendants, and earrings. It has historical value in folklore and as a June birthstone.

Geological facts

Ancient Romans believed moonstone was formed from frozen rays of moonlight. It is the state gem of Florida (commemorating the Moon landings). High-quality specimens with a strong blue flash are significantly more valuable than common white ones.

Field identification & locations

Identify by looking for 'adularescence'—a light effect that moves across the stone's surface as it is rotated. It is commonly found in Sri Lanka, India, Myanmar, and Madagascar. In the field, it is distinguished from quartz by its cleavage and softer hardness.

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Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Epidote

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metamorphic

Nephrite Jade

Nephrite

Mineral/Rock

Banded Gneiss (River Rock/Pebble)

Gneiss (specifically a banded variety often found as a river rock)

Metamorphic Rock

Green Apatite on Albite

Fluorapatite [Ca5(PO4)3F] on Albite [Na(AlSi3O8)]

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Epidote - Ca2(Al2,Fe3+)3(SiO4)3(OH)

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