mineral

Moonstone

Orthoclase (KAlSi3O8), specifically the variety showing adularescence

Hardness: 6.0 – 6.5 (Mohs), Color: Colorless to white with a blue or white sheen, Luster: Vitreous to pearly, Crystal structure: Monoclinic, Cleavage: Perfect in two directions, Specific gravity: 2.56 – 2.59

Hardness: 6

Identified March 25, 2026More mineral →

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Physical properties

Formation & geological history

Formed in igneous and metamorphic rocks, specifically within pegmatites. It consists of alternating layers of orthoclase and albite; when light falls between these layers, it scatters, causing the optical effect known as adularescence.

Uses & applications

Predominantly used as a gemstone in jewelry (rings, pendants, earrings), crystal healing practices, and as a popular specimen for mineral collectors.

Geological facts

In Roman mythology, it was believed moonstone was formed from frozen beams of moonlight. It is the Florida State Gemstone (commemorating the Apollo moon landings) and is a traditional birthstone for June.

Field identification & locations

Identify by its 'adularescence'—a milky bluish glow that moves across the surface as the stone is turned. It is commonly found in Sri Lanka, India, Myanmar, and Madagascar. Collectors look for high clarity 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