gemstone

Moonstone

Orthoclase / Feldspar (KAlSi3O8)

Hardness: 6 on the Mohs scale; Color: Silvery-white to bluish, grey, peach, or green with a characteristic adularescence (milky, balloon-like light sheen); Luster: Vitreous to pearly; Crystal structure: Monoclinic; Cleavage: Perfect in two directions; Specific gravity: 2.56-2.58

Hardness: 6 on the Mohs scale
Luster: Vitreous to pearly

Identified July 29, 2026More gemstone →

Explore Moonstone in the encyclopedia →

Identify your own rocks.

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

App Store Google Play

Physical properties

Formation & geological history

Forms in igneous rocks like granites and pegmatites, as well as in metamorphic rocks, when molten rock cools slowly allowing potassium and sodium feldspar to demix into alternating microscopic layers that scatter light.

Uses & applications

Popularly cut into cabochons for rings, earrings, and pendants; used in crystal healing and metaphysical practices; valued as a collector specimen.

Geological facts

Moonstone gets its name from the shimmering visual effect caused by light diffraction within a micro-structure consisting of regular feldspar layer stacking. It has been used in jewelry for centuries, notably gaining massive popularity during the Art Nouveau period.

Field identification & locations

Easily identified by its characteristic floating blue or white sheen (adularescence) when rotated under light. Major sources include Sri Lanka, India, Madagascar, Myanmar, and the United States.