mineral

Moonstone (Feldspar)

Orthoclase feldspar, (K,Na)AlSi3O8

AI-generated identification · may be incorrect

Hardness: 6-6.5 (Mohs), Color: Colorless to white with blue/multi-colored adularescence, Luster: Vitreous to pearly, Crystal structure: Monoclinic, Cleavage: Two directions at 90 degrees, Specific gravity: 2.56-2.59

Hardness: 6-6

Identified April 19, 2026More mineral →

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Physical properties

Formation & geological history

Formed in igneous and metamorphic rocks. Its unique shimmer, called adularescence, is caused by the intergrowth of two different feldspars (orthoclase and albite) which separate as the rock cools, causing light to scatter.

Uses & applications

Primarily used as a gemstone in jewelry (rings, pendants, earrings) and as a pocket stone for collectors. It is the birthstone for June.

Geological facts

Ancient Romans believed moonstone was formed from frozen beams of moonlight. It is known for its 'schiller' effect, where light appears to billow across the surface of the stone like moonlight on water.

Field identification & locations

Identify by its distinctive blue or white sheen (adularescence) that moves when the stone is rotated. Commonly found in Sri Lanka, India, Myanmar, and Madagascar. Look for the 'glow' below the surface of the stone.