mineral

Moonstone

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

Hardness: 6.0-6.5 on Mohs scale; Color: Colorless to white with a blue or white schiller; Luster: Vitreous to pearly; Crystal structure: Monoclinic; Cleavage: Perfect at two directions; Specific Gravity: 2.56-2.59

Hardness: 6
Color: Colorless to white with a blue or white schiller
Luster: Vitreous to pearly

Identified March 25, 2026More mineral →

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Physical properties

Formation & geological history

Formed from molten rock (magma) that cools slowly, allowing two different types of feldspar to intergrow. As the rock cools, the minerals separate into alternating layers. It is primarily found in pegmatite veins and metamorphic rocks.

Uses & applications

Predominantly used as a gemstone in jewelry (rings, pendants, and earrings) and as a lapidary material for collectors.

Geological facts

The visual effect seen in moonstone is called adularescence, caused by light scattering between microscopic layers of orthoclase and albite. It has been used in jewelry for centuries, particularly by the Romans and during the Art Nouveau period.

Field identification & locations

Identify in the field by its distinct 'glow' or shimmer when rotated under light. Commonly found in Sri Lanka, India, Myanmar, and Madagascar. Collectors look for high transparency and a strong blue 'flash'.

Other mineral specimens

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Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

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)]

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Epidote

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

mineral