mineral

Moonstone

Orthoclase feldspar ((K,Na)AlSi3O8)

Hardness: 6.0-6.5 on Mohs scale; Color: Creamy white with yellow/tan inclusions and blue or white adularescence; Luster: Vitreous to pearly; Crystal structure: Monoclinic; Cleavage: Perfect in two directions.

Hardness: 6
Luster: Vitreous to pearly

Identified May 29, 2026More mineral →

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Physical properties

Formation & geological history

Formed from intergrown layers of orthoclase and albite. As the cooling mineral cools, the two minerals separate into stacked layers. These layers scatter light, creating the 'moonlight' effect known as adularescence.

Uses & applications

Primarily used in jewelry (cabochons, rings, pendants) and as a healing stone in metaphysical communities. It is the birthstone for June.

Geological facts

Ancient Romans theorized that moonstone was formed from frozen rays of moonlight. It is the state gem of Florida, despite the mineral not being naturally found there (celebrating the Moon landings).

Field identification & locations

Identify in the field by its distinct schiller effect or adularescence when rotated under light. Common locations include Sri Lanka, India, Madagascar, and Myanmar. Look for the characteristic 'centipede' inclusions under magnification.