mineral

Moonstone

Adularia (Potassium Aluminum Silicate, KAlSi3O8)

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 →

Identify your own rocks.

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

App Store Google Play

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.

Other mineral specimens

See all

Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Epidote

Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)

metamorphic

Nephrite Jade

Nephrite

Mineral/Rock

Banded Gneiss (River Rock/Pebble)

Gneiss (specifically a banded variety often found as a river rock)

Metamorphic Rock

Green Apatite on Albite

Fluorapatite [Ca5(PO4)3F] on Albite [Na(AlSi3O8)]

mineral

Epidote

Epidote - Ca2(Al2,Fe3+)3(SiO4)3(OH)

mineral