gemstone

Moonstone (Rainbow Moonstone with Tourmaline)

White Labradorite (Feldspar variety) - (Na,Ca)(Al,Si)4O8

Hardness: 6.0-6.5 (Mohs scale); Color: White to translucent with blue schiller; Luster: Pearly to vitreous; Crystal system: Triclinic; Specific gravity: 2.6-2.7. Often contains black tourmaline inclusions.

Hardness: 6
Color: White to translucent with blue schiller
Luster: Pearly to vitreous

Identified July 19, 2026More gemstone →

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Physical properties

Formation & geological history

Forms in pegmatites and metamorphic rocks through slow cooling that allows the exsolution of different feldspar layers. The rainbow varieties are geologically related to anorthosite formations.

Uses & applications

Primarily used in jewelry (cabochons), ornamental carvings, and by crystal collectors for aesthetic and metaphysical properties.

Geological facts

True moonstone is Orthoclase, but most modern 'Rainbow Moonstone' is actually a white variety of Labradorite. The blue flash seen on the surface is an optical phenomenon called labradorescence (or adularescence).

Field identification & locations

Identify by looking for a blue or multicolored sheen (adularescence) when rotated under light. Common locations include India and Sri Lanka. Collectors look for high clarity and strong blue flashes.

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Silicon Dioxide (SiO2) with Hematite inclusions

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