mineral

Moonstone

Orthoclase Feldspar ((K,Na)AlSi3O8)

Hardness: 6.0-6.5 on Mohs scale; Color: Creamy white to pale yellow; Luster: Vitreous to pearly; Crystal structure: Monoclinic; Cleavage: Perfect in two directions; Specific gravity: 2.56-2.59

Hardness: 6
Color: Creamy white to pale yellow
Luster: Vitreous to pearly

Identified May 16, 2026More mineral →

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Physical properties

Hardness: 6.0-6.5 on Mohs scale; Color: Creamy white to pale yellow; Luster: Vitreous to pearly; Crystal structure: Monoclinic; Cleavage: Perfect in two directions; Specific gravity: 2.56-2.59

Formation & geological history

Formed in igneous and metamorphic rocks through the cooling of silica-rich magmas. The characteristic shimmer (adularescence) occurs from the intergrowth of two types of feldspar, orthoclase and albite, which separate during cooling.

Uses & applications

Primarily used in jewelry as cabochons, rings, and pendants. It is also a popular collector's mineral and is used in holistic practices.

Geological facts

Ancient Romans believed moonstone was formed from frozen rays of moonlight. It is one of the birthstones for June and is the state gem of Florida to commemorate the moon landings.

Field identification & locations

Identify in the field by its distinct schiller effect or adularescence (a milky sheen). Commonly found in Sri Lanka, India, Myanmar, Madagascar, and parts of the United States. It shows a 'billowy' light effect when rotated.