mineral

Moonstone

Orthoclase (KAlSi3O8) with inclusions of Albite (NaAlSi3O8)

Hardness: 6.0-6.5; Color: Colorless to white with blue/white adularescence; Luster: Vitreous to pearly; Crystal structure: Monoclinic; Cleavage: Perfect in two directions; Specific gravity: 2.56-2.59

Hardness: 6
Color: Colorless to white with blue/white adularescence
Luster: Vitreous to pearly

Identified March 16, 2026More mineral →

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Physical properties

Hardness: 6.0-6.5; Color: Colorless to white with blue/white adularescence; Luster: Vitreous to pearly; Crystal structure: Monoclinic; Cleavage: Perfect in two directions; Specific gravity: 2.56-2.59

Formation & geological history

Formed in plutonic igneous rocks (pegmatites) where cooling magma allows orthoclase and albite to separate into alternating layers, creating light interference.

Uses & applications

Primarily used in jewelry as cabochons, beads, and gems; also a popular specimen for collectors due to its optical effects.

Geological facts

The shimmering effect is called adularescence, caused by light scattering between microscopic layers of different feldspar minerals. It is the state gem of Florida to commemorate the Apollo moon landings.

Field identification & locations

Identify in the field by its distinct blue or white billowy light reflection when rotated. Commonly found in Sri Lanka, India, Myanmar, and Madagascar.

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