mineral

Moonstone

Orthoclase Feldspar (KAlSi3O8)

Hardness: 6-6.5 Mohs scale, Color: Transparent to translucent white/blue, Luster: Vitreous to pearly, Crystal structure: Monoclinic, Cleavage: Perfect in two directions, Specific gravity: 2.56-2.59

Hardness: 6-6

Identified April 19, 2026More mineral →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Hardness: 6-6.5 Mohs scale, Color: Transparent to translucent white/blue, Luster: Vitreous to pearly, Crystal structure: Monoclinic, Cleavage: Perfect in two directions, Specific gravity: 2.56-2.59

Formation & geological history

Formed in high-temperature igneous and metamorphic environments, specifically pegmatites. The visual effect (adularescence) is caused by the intergrowth of two types of feldspar that separate as the mineral cools.

Uses & applications

Primarily used in jewelry (cabochons, rings, pendants) and popular among crystal collectors for its aesthetic and perceived metaphysical properties.

Geological facts

Moonstone is the state gem of Florida to commemorate the moon landings, despite not being found naturally there. The high-quality blue sheen specimens are highly sought after.

Field identification & locations

Identify in the field by its distinct adularescence (a milky sheen or glow that moves across the surface). Most commonly found in Sri Lanka, India, Myanmar, and Madagascar.