mineral

Moonstone

Adularia / Orthoclase (KAlSi3O8)

Hardness: 6-6.5 Mohs scale. Color: Colorless to white with blue sheen (adularescence). Luster: Vitreous to pearly. Crystal structure: Monoclinic. Cleavage: Perfect in two directions. Specific gravity: 2.56-2.59.

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

Identified May 10, 2026More mineral →

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Physical properties

Formation & geological history

Formed in igneous or metamorphic environments through slow cooling of magma, allowing orthoclase and albite to separate into alternating layers which cause the light interference known as adularescence.

Uses & applications

Primarily used in jewelry for cabochons, beads, and engravings. It is also a popular collector's mineral and used in crystal healing practices.

Geological facts

Moonstone is the state gem of Florida to commemorate the moon landing. The billowy blue light effect is technically called adularescence, named after Mt. Adula in Switzerland.

Field identification & locations

Identify in the field by its distinct pearly luster and blue flash. Common locations include Sri Lanka, India, Myanmar, and Madagascar. Collectors look for high transparency and a strong blue sheen centered on the stone.