mineral

Moonstone

Orthoclase (Potassium Aluminum Silicate, KAlSi3O8)

Hardness: 6.0-6.5 (Mohs); Color: Colorless to white with blue or white adularescence (sheen); Luster: Vitreous to pearly; Crystal structure: Monoclinic; Cleavage: Perfect in two directions; Specific Gravity: 2.56-2.59

Hardness: 6
Color: Colorless to white with blue or white adularescence (sheen)
Luster: Vitreous to pearly

Identified April 22, 2026More mineral →

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Physical properties

Formation & geological history

Formed in igneous or metamorphic environments when two types of feldspar (orthoclase and albite) intergrow and then separate into layers as the magma cools. Light scattering between these microscopic layers creates the glow.

Uses & applications

Primarily used as a gemstone in jewelry (rings, pendants, earrings) and as a healing stone in holistic practices. It is the birthstone for June.

Geological facts

The shimmering effect of moonstone is called 'adularescence.' It was highly popular during the Art Nouveau period and was famously used by jeweler René Lalique. Ancient Romans believed moonstones were formed from frozen moonbeams.

Field identification & locations

Identify in the field by its characteristic blue or white pearly sheen when rotated under light, combined with its 6.0-6.5 hardness. Commonly found in Sri Lanka, India, Myanmar, and Madagascar.

Other mineral specimens

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Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Schist

Metamorphic

Epidote

Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)

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)]

mineral