mineral

Moonstone

Potassium Aluminum Silicate (KAlSi3O8)

Hardness: 6.0-6.5 (Mohs scale); Color: Colorless to white, peach, or bluish; Luster: Vitreous to pearly; Crystal structure: Monoclinic; Cleavage: Perfect in two directions; Adularescence (inner glow).

Hardness: 6
Color: Colorless to white, peach, or bluish
Luster: Vitreous to pearly

Identified March 24, 2026More mineral →

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Physical properties

Formation & geological history

Formed in igneous and metamorphic rocks from feldspar cooling, where orthoclase and albite separate into microscopic layers. Age varies by location, often associated with Precambrian to Mesozoic formations.

Uses & applications

Primarily used in jewelry (rings, pendants) and for metaphysical/collecting purposes due to its unique optical properties.

Geological facts

The characteristic 'glow' is called adularescence, caused by light scattering between thin layers of orthoclase and albite within the mineral. It is the state gemstone of Florida.

Field identification & locations

Identify by its 'milky' or pearly sheen that moves as the stone is rotated. Commonly found in Sri Lanka, India, Myanmar, and Madagascar. Collectors look for stones with a strong blue sheen and high transparency.