mineral

Moonstone

Orthoclase Feldspar ((K,Na)AlSi3O8)

Hardness: 6-6.5 Mohs scale; Color: White to colorless with blue or white adularescence; Luster: Vitreous to pearly; Crystal structure: Monoclinic; Cleavage: Two directions at 90 degrees; Specific Gravity: 2.56-2.59

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

Identified March 25, 2026More mineral →

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Physical properties

Formation & geological history

Formed in plutonic igneous rocks (pegmatites) and metamorphic rocks. The characteristic 'glow' occurs as the mineral cools and intergrowths of orthoclase and albite separate into microscopic layers, which scatter light.

Uses & applications

Primarily used in jewelry as cabochons, rings (as pictured), and pendants. High-quality specimens are highly sought after by gemstone collectors.

Geological facts

Ancient Romans and Greeks theorized that moonstone was formed from frozen beams of moonlight. It is the Florida State Gemstone and one of the modern birthstones for June.

Field identification & locations

Identify by 'adularescence' (a billowy white/blue light effect). Found commonly in Sri Lanka, India, Myanmar, and Madagascar. Collectors should look for higher transparency and strong blue sheen.