mineral

Moonstone (Feldspar variety)

Orthoclase Feldspar (KAlSi3O8)

Hardness: 6.0–6.5 Mohs scale; Color: Colorless to white, gray, or blue; Luster: Vitreous to pearly; Crystal Structure: Monoclinic; Cleavage: Perfect in two directions; Features adularescence (a ghostly sheen).

Hardness: 6
Color: Colorless to white, gray, or blue
Luster: Vitreous to pearly

Identified April 4, 2026More mineral →

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Physical properties

Formation & geological history

Formed in igneous and metamorphic rocks, specifically within pegmatites. The characteristic sheen is caused by the intergrowth of two types of feldspar (orthoclase and albite) that separate as the magma cools, creating a light-scattering effect.

Uses & applications

Primarily used as a gemstone in jewelry (rings, pendants, earrings), and widely collected by mineral enthusiasts and those interested in metaphysical properties.

Geological facts

Ancient Romans believed moonstone was formed from frozen rays of moonlight. It is the Florida State Gemstone (commemorating the Apollo moon landings), despite not being naturally occurring in the state.

Field identification & locations

Identify by its 'shiller' effect (adularescence) when rotated under light. Commonly found in Sri Lanka, India, Myanmar, and Madagascar. In the field, look for the play of color and its distinct right-angle cleavage faces.

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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)

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