mineral

Polished labradorite cabochon

Labradorite, calcium-rich plagioclase feldspar; approximately (Ca,Na)(Al,Si)₄O₈

AI-generated identification · may be incorrect

Hardness 6–6.5 Mohs; dark gray to black body color with blue-green iridescent labradorescence, vitreous luster, triclinic crystal structure, and two good cleavage directions. The rounded, glossy form is a polished cabochon, likely set-free rather than rough rock.

Identified August 22, 2026More mineral →

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Physical properties

Formation & geological history

Forms in mafic igneous rocks such as gabbro, anorthosite, and basalt when plagioclase crystals cool and exsolve into fine lamellae that produce optical color flashes. Major deposits occur in Madagascar, Finland, Canada, Norway, and Russia; ages range from Precambrian to younger igneous bodies.

Uses & applications

Used for cabochon jewelry, carvings, ornamental objects, and mineral collecting; it is not generally used as a construction aggregate when gem-quality material is present.

Geological facts

Its changing blue, green, or gold flash is caused by light interference between microscopic feldspar lamellae, not surface paint. Strong labradorescence is the main quality factor.

Field identification & locations

Identify by rotating the stone under a strong light: genuine labradorite shows directional internal flashes and commonly contains gray-black mottling. Typical polished cabochon value is $10–$75; vivid, clean, large stones may reach $100–$300.