mineral

Iridescent labradorite cabochon

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

AI-generated identification · may be incorrect

Typically gray to dark gray with blue, green, gold, or violet labradorescence; vitreous to pearly luster, triclinic crystal structure, perfect cleavage in two directions, Mohs hardness 6–6.5, and specific gravity about 2.68–2.72.

Identified August 24, 2026More mineral →

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Physical properties

Formation & geological history

Forms as an igneous feldspar in mafic intrusive rocks such as gabbro and anorthosite, crystallizing as magma cools. Most gem-quality material is associated with Precambrian anorthosite terrains.

Uses & applications

Used for cabochons, beads, carvings, and ornamental stone; larger slabs are used decoratively in interiors. Its value comes mainly from strong, broad flashes of color and attractive polish.

Geological facts

The rainbow-like effect is labradorescence, caused by light interference within microscopic lamellae formed during feldspar cooling. The pictured rectangular, polished piece is likely cut and shaped rather than naturally crystal-faced.

Field identification & locations

Identify it by gray body color, subdued cleavage, and shifting blue-gold-violet flashes when tilted under light; common sources include Labrador, Canada, Madagascar, Finland, Norway, and Russia. Avoid harsh impacts because of cleavage.