mineral

Moonstone (Orthoclase Feldspar)

Orthoclase (KAlSi3O8) with Albite (NaAlSi3O8)

Hardness: 6-6.5 (Mohs scale), Color: Creamy white to pale tan, Luster: Vitreous to pearly, Crystal structure: Monoclinic, Cleavage: Two directions at nearly 90 degrees, Specific gravity: 2.56-2.59

Hardness: 6-6

Identified June 6, 2026More mineral →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Hardness: 6-6.5 (Mohs scale), Color: Creamy white to pale tan, Luster: Vitreous to pearly, Crystal structure: Monoclinic, Cleavage: Two directions at nearly 90 degrees, Specific gravity: 2.56-2.59

Formation & geological history

Formed in igneous and metamorphic environments, specifically pegmatites and granites. The characteristic 'glow' or adularescence occurs as the cooling mineral separates into alternating layers of orthoclase and albite, which scatter light.

Uses & applications

Primarily used as a gemstone in jewelry (rings, pendants, earrings) and as a stone for metaphysical collecting and spiritual practices.

Geological facts

Ancient Romans believed moonstone was formed from frozen rays of the moon. It is the Florida State Gemstone (commemorating the Apollo moon landings) even though it is not naturally found there.

Field identification & locations

Identify by its 'schiller' effect or adularescence (a ghostly internal sheen). In the field, look for crystalline faces and its distinct right-angle cleavage. Common in Sri Lanka, India, Myanmar, and Madagascar.

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