mineral

Moonstone

Orthoclase (KAlSi3O8) with Albite (NaAlSi3O8) intergrowths

Hardness: 6-6.5 (Mohs scale), Color: White, cream, or translucent with blue/white sheen, Luster: Vitreous to pearly, Crystal structure: Monoclinic, Cleavage: Perfect in two directions, Specific Gravity: 2.56-2.59

Hardness: 6-6

Identified June 28, 2026More mineral →

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Physical properties

Formation & geological history

Formed in plutonic igneous rocks (pegmatites) when potassium-rich feldspar and sodium-rich feldspar separate as the lava cools into alternating layers, causing the scattering of light known as adularescence.

Uses & applications

Primarily used in jewelry for cabochons and rings; also highly valued by mineral collectors for its unique optical properties.

Geological facts

Moonstone is the state gem of Florida to commemorate the Apollo moon landings, even though it isn't naturally found there. In ancient Rome and India, it was believed to be created from solidified moonbeams.

Field identification & locations

Identify in the field by its distinct adularescence (a ghostly glow just under the surface) and two planes of cleavage at nearly 90 degrees. Commonly found in Sri Lanka, India, Myanmar, and Madagascar.

Other mineral specimens

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Arenite (SiO2 based)

sedimentary

Schist

Metamorphic

Epidote

Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)

metamorphic

Gypsum (variety Selenite or Alabaster)

Calcium sulfate dihydrate (CaSO4·2H2O)

Mineral

Nephrite Jade

Nephrite

Mineral/Rock

Banded Gneiss (River Rock/Pebble)

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Metamorphic Rock