Rock Identifier
Tumbled banded stone, likely labradorite or larvikite (Plagioclase feldspar aggregate; commonly labradorite (labradorescence) or larvikite) — mineral
mineral

Tumbled banded stone, likely labradorite or larvikite

Plagioclase feldspar aggregate; commonly labradorite (labradorescence) or larvikite

AI-generated identification · may be incorrect

Rounded and polished, gray-brown with fine linear banding and a blue flash; vitreous to pearly luster. Hardness about 6–6.5 Mohs, imperfect cleavage, and specific gravity roughly 2.65–2.75.

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Physical properties

Rounded and polished, gray-brown with fine linear banding and a blue flash; vitreous to pearly luster. Hardness about 6–6.5 Mohs, imperfect cleavage, and specific gravity roughly 2.65–2.75.

Formation & geological history

Likely cut from a feldspar-rich igneous rock and mechanically tumbled; labradorite forms in slowly cooled mafic igneous bodies, generally Precambrian to Mesozoic in age. The image alone cannot distinguish it confidently from larvikite or another feldspar-rich stone.

Uses & applications

Used as a decorative tumbled stone, cabochon, carving material, and occasionally in jewelry; larger labradorite and larvikite are used as architectural stone.

Geological facts

The blue sheen is structural iridescence caused by light interference within microscopic feldspar lamellae, not surface paint. A strong flash when rotated is characteristic of labradorite.

Field identification & locations

Common sources include Madagascar, Finland, Norway, Canada, and Russia. Confirm with a bright-light rotation test, feldspar cleavage, and a hardness test; avoid scratching polished surfaces.