mineral

Moonstone

Orthoclase Feldspar ((K,Na)AlSi3O8) with Albite inclusions

AI-generated identification · may be incorrect

Hardness: 6-6.5 Mohs scale; Color: Colorless to white with blue or white schiller (adularescence); Luster: Vitreous to pearly; Crystal Structure: Monoclinic; Cleavage: Two directions at 90 degrees; Specific Gravity: 2.56-2.59

Hardness: 6-6
Luster: Vitreous to pearly

Identified February 24, 2026More mineral →

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Physical properties

Formation & geological history

Formed in plutonic igneous rocks (pegmatites) and metamorphic rocks. The characteristic glow arises from the intergrowth of two types of feldspar that separate as the magma cools, causing light to scatter.

Uses & applications

Primarily used as a gemstone in jewelry (cabochons, beads, and rings) and as a popular collector specimen due to its optical effects.

Geological facts

Moonstone is the most famous variety of orthoclase feldspar. In ancient Roman and Greek mythology, it was believed to be made of solidified moonbeams. It is the Florida State Gemstone, designated to commemorate the Moon landing.

Field identification & locations

Identified in the field by its distinct adularescence (a ghostly blue or white sheen), light weight relative to appearance, and cleavage. Found commonly in Sri Lanka, India, Madagascar, and Myanmar.