mineral

Tumbled labradorite

Labradorite, plagioclase feldspar (approximately NaAlSi₃O₈–CaAl₂Si₂O₈)

AI-generated identification · may be incorrect

Typically gray to dark gray with a vitreous-to-pearly luster, granular crystal structure, and prominent iridescent blue flash (labradorescence); Mohs hardness 6–6.5, with two cleavage directions. The pictured polished stone appears consistent with labradorite, though lighting limits certainty.

Identified September 8, 2026More mineral →

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Physical properties

Formation & geological history

Forms in slow-cooling mafic igneous rocks such as gabbro, anorthosite, and basalt, where feldspar exsolution creates optical color effects. Major deposits occur in Madagascar, Finland, Canada, Norway, and Mexico; ages vary by locality from Precambrian to younger igneous settings.

Uses & applications

Used as a decorative stone, cabochon, beads, carvings, and tumbled specimens; large slabs are occasionally used architecturally. Common tumbles generally have modest value.

Geological facts

Its blue, green, gold, or violet flash results from light interference in microscopic feldspar lamellae, not surface coating. Strong labradorescence is most visible when the stone is rotated under directional light.

Field identification & locations

Identify by dark gray body color, polished glassy surface, and shifting internal flashes; distinguish it from obsidian, which lacks feldspar cleavage and characteristic flash. Estimated value: $3–$20 for a small tumble, or $20–$100+ for strongly flashy material.