mineral
Polished labradorite
Labradorite, calcium-rich plagioclase feldspar (approximately Ca0.5–0.7Na0.5–0.3Al1.5–1.7Si2.5–2.3O8)
AI-generated identification · may be incorrectHardness 6–6.5 Mohs; gray-brown body color with blue-green iridescent flash (labradorescence), vitreous luster, triclinic crystal structure, and two good cleavage directions. The rounded shape indicates tumbling or polishing.
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Physical properties
Hardness 6–6.5 Mohs; gray-brown body color with blue-green iridescent flash (labradorescence), vitreous luster, triclinic crystal structure, and two good cleavage directions. The rounded shape indicates tumbling or polishing.
Formation & geological history
Forms in mafic igneous rocks such as basalt, gabbro, and anorthosite as magma cools; many gem-quality examples formed in Precambrian anorthosite complexes. Major sources include Madagascar, Finland, Canada, Norway, and Russia.
Uses & applications
Used for cabochons, beads, carvings, polished stones, and ornamental countertops; valued more for strong, broad blue or multicolor flash than for transparency.
Geological facts
Its iridescence results from light interference in thin, compositionally layered lamellae produced during feldspar exsolution. Spectrolite is the particularly vivid Finnish variety.
Field identification & locations
Identify by gray base color, feldspar-like cleavage, and directional blue flash that changes as the stone moves; a glassy imitation lacks natural cleavage and internal lamellar effects. The pictured specimen appears tumbled and polished.
