mineral

Moonstone

Orthoclase Feldspar ((K,Na)AlSi3O8) with Albite

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

Hardness: 6
Color: White to translucent with blue or white adularescence
Luster: Vitreous to pearly

Identified June 2, 2026More mineral →

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Physical properties

Formation & geological history

Formed in plutonic and metamorphic rocks (pegmatites). It results from the intergrowth of two types of feldspar that separate as the magma cools, creating thin alternating layers that scatter light.

Uses & applications

Primarily used in jewelry (as cabochons) and as a decorative gemstone. It is the birthstone for June and highly valued by collectors for its optical effects.

Geological facts

The shimmering light effect is called adularescence, caused by the diffraction of light as it hits tiny layers of albite within the orthoclase. It was highly popular during the Art Nouveau period with jewelers like René Lalique.

Field identification & locations

Identify by its characteristic 'glow' or sheen when rotated under light. Often found in Sri Lanka, India, Myanmar, and Madagascar. Collectors look for high transparency and a strong blue sheen.

Other mineral specimens

See all

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

Biotite Schist

Biotite-rich Schist [K(Mg,Fe)3AlSi3O10(F,OH)2]

metamorphic