mineral

Grey Moonstone

Potassium Aluminum Silicate (KAlSi3O8)

Hardness: 6-6.5 on Mohs scale; Color: Gray, silvery-grey, brownish-grey; Lustre: Vitreous to pearly; Crystal structure: Monoclinic; Specific Gravity: 2.56-2.59; Cleavage: Perfect in two directions

Hardness: 6-6
Color: Gray, silvery-grey, brownish-grey

Identified April 4, 2026More mineral →

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Physical properties

Hardness: 6-6.5 on Mohs scale; Color: Gray, silvery-grey, brownish-grey; Lustre: Vitreous to pearly; Crystal structure: Monoclinic; Specific Gravity: 2.56-2.59; Cleavage: Perfect in two directions

Formation & geological history

Formed in plutonic igneous rocks (pegmatites) through the cooling of magma. As it cools, the intergrowth of orthoclase and albite creates the characteristic 'adularescence' (light play). Geological age varies by deposit, spanning hundreds of millions of years.

Uses & applications

Primarily used in jewelry (cabochons, rings, pendants), New Age practices, and as a popular collector's mineral.

Geological facts

Also known as 'New Moonstone' because its dark, mysterious glow is reminiscent of the moon's phase. The shimmering effect is caused by light scattering between microscopic layers of different feldspar types within the stone.

Field identification & locations

Identify by its 'adularescence'—a glow that appears to move across the surface as the stone is turned. It is commonly found in Sri Lanka, India, Myanmar, and Madagascar. Collectors look for a clear, moving sheen without heavy internal fractures.

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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

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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