mineral

Moonstone

Adularia (Potassium Aluminum Silicate, KAlSi3O8)

AI-generated identification · may be incorrect

Hardness: 6.0–6.5 (Mohs scale); Color: White, colorless, or pearly with blue/white adularescence; Luster: Vitreous to pearly; Crystal structure: Monoclinic; Cleavage: Two directions at 90 degrees; Specific gravity: 2.56–2.59

Hardness: 6
Color: White, colorless, or pearly with blue/white adularescence
Luster: Vitreous to pearly

Identified March 23, 2026More mineral →

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Physical properties

Formation & geological history

Formed from orthoclase and albite feldspar layers that separate as the mineral cools from a molten state. The alternating layers scatter light to create its characteristic glow. It is found in igneous and metamorphic rocks across various geological ages.

Uses & applications

Primarily used in jewelry (beads, cabochons, rings) and as a highly sought-after specimen for crystal collecting and lapidary arts.

Geological facts

The shimmering effect is called 'adularescence,' named after Mt. Adular in Switzerland. It was immensely popular during the Art Nouveau period and is the designated state gem of Florida to commemorate the moon landings.

Field identification & locations

Identify in the field by its distinct billowy internal light or 'sheen.' It is commonly sourced from Sri Lanka, India, Myanmar, and Madagascar. For collectors, higher transparency and a strong blue sheen increase rarity.