gemstone

Moonstone cabochon (probable)

Adularescent feldspar, usually orthoclase–albite intergrowth (KAlSi3O8–NaAlSi3O8)

AI-generated identification · may be incorrect

Polished oval cabochon with milky white body and a soft internal glow, consistent with adularescence; vitreous-to-pearly luster and no visible crystal faces. Hardness about 6–6.5 Mohs, specific gravity roughly 2.55–2.60, with two good cleavage directions.…

Identified August 23, 2026More gemstone →

Explore Moonstone cabochon (probable) in the encyclopedia →

Identify your own rocks.

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

App Store Google Play

Physical properties

Formation & geological history

Forms in potassium-rich pegmatites and related igneous rocks when feldspar exsolves into fine intergrowths that scatter light. Important sources include Sri Lanka, India, Madagascar, Myanmar, and Tanzania; age varies with the host rock.

Uses & applications

Used primarily in cabochon jewelry and mineral collecting. Commercial value is generally modest unless the blue sheen is strong, broad, and evenly visible.

Geological facts

The floating glow is called adularescence and changes with viewing angle; it is not the same phenomenon as labradorescence in labradorite.

Field identification & locations

Identify by the moving internal sheen, low-to-moderate hardness, and feldspar cleavage; glass or synthetic opalite can look similar. The reported Andhra Pradesh location is plausible for feldspar-bearing pegmatites, but the photograph alone cannot confirm natural moonstone or species.