Rock Identifier
Likely labradorite-bearing rocks (Labradorite, a plagioclase feldspar (approximately NaAlSi₃O₈–CaAl₂Si₂O₈), possibly in mafic host rock) — mineral
mineral

Likely labradorite-bearing rocks

Labradorite, a plagioclase feldspar (approximately NaAlSi₃O₈–CaAl₂Si₂O₈), possibly in mafic host rock

AI-generated identification · may be incorrect

The specimens are gray-brown, coarse-grained and partly polished, with dark feldspar and possible blue-green schiller. Labradorite has Mohs hardness 6–6.5, vitreous to pearly luster, triclinic crystals, and two cleavages near 90°; exact identification is uncertain from the photograph.

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Physical properties

The specimens are gray-brown, coarse-grained and partly polished, with dark feldspar and possible blue-green schiller. Labradorite has Mohs hardness 6–6.5, vitreous to pearly luster, triclinic crystals, and two cleavages near 90°; exact identification is uncertain from the photograph.

Formation & geological history

Forms by crystallization of basaltic to anorthositic magma, commonly in Precambrian massif complexes; labradorescence arises from microscopic exsolution lamellae within feldspar.

Uses & applications

Used as an architectural facing stone, countertops, aggregate, carvings, cabochons and ornamental tumbled stones; attractive flash increases jewelry value.

Geological facts

The optical color flash is not surface coating but interference from internal lamellae. The rough gray specimen may be labradorite-rich anorthosite or another feldspathic mafic rock.

Field identification & locations

Check for blue, green or gold flash when rotated under a strong light, feldspar cleavage, and hardness below quartz; common sources include Labrador, Canada, Madagascar, Finland and Norway.