mineral

Moonstone

Orthoclase Feldspar ((K,Na)AlSi3O8)

Hardness: 6-6.5 Mohs; Color: Colorless to white with blue/white adularescence (sheen); Luster: Vitreous to pearly; Crystal structure: Monoclinic; Cleavage: Perfect in two directions

Hardness: 6-6
Color: Colorless to white with blue/white adularescence (sheen)
Luster: Vitreous to pearly

Identified June 28, 2026More mineral →

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Physical properties

Hardness: 6-6.5 Mohs; Color: Colorless to white with blue/white adularescence (sheen); Luster: Vitreous to pearly; Crystal structure: Monoclinic; Cleavage: Perfect in two directions

Formation & geological history

Forms in igneous and metamorphic rocks, specifically in pegmatites where slow cooling allows crystal growth. The characteristic sheen (adularescence) is caused by the intergrowth of two types of feldspar that separate during cooling.

Uses & applications

Primarily used in jewelry, lapidary arts, and as a popular gemstone for collectors and metaphysical belief practices.

Geological facts

Ancient Romans believed moonstones were formed from frozen droplets of moonlight. It is the birthstone for the month of June.

Field identification & locations

Identify by its unique 'billowing' blue or white light effect when rotated. Commonly found in Sri Lanka, India, Myanmar, and Madagascar. Avoid ultrasonic cleaning due to cleavage planes.