Rock Identifier
Labradorite ((Ca,Na)(Al,Si)4O8 (Plagioclase Feldspar)) — mineral
mineral

Labradorite

(Ca,Na)(Al,Si)4O8 (Plagioclase Feldspar)

Hardness: 6-6.5 on the Mohs scale; Color: Gray-green, dark grey, brown, or black with iridescent flashes of blue, green, gold, and copper (labradorescence); Luster: Vitreous to pearly; Crystal Structure: Triclinic; Cleavage: Perfect in two directions.

Hardness
6-6
Luster
Vitreous to pearly
Identified More mineral
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Physical properties

Hardness: 6-6.5 on the Mohs scale; Color: Gray-green, dark grey, brown, or black with iridescent flashes of blue, green, gold, and copper (labradorescence); Luster: Vitreous to pearly; Crystal Structure: Triclinic; Cleavage: Perfect in two directions.

Formation & geological history

Forms primarily in mafic igneous rocks such as basalt, gabbro, and anorthosite, as well as in metamorphic and pegmatitic environments through slow cooling of magma.

Uses & applications

Commonly used as a gemstone in jewelry, for decorative items, and as a popular specimen among crystal collectors.

Geological facts

Labradorite exhibits a unique optical phenomenon called labradorescence, which is caused by the light interference of microscopic lamellar intergrowths.

Field identification & locations

Easily identified by its dark base color and striking flashes of iridescent color when rotated under a light source. Found famously in Labrador, Canada, as well as Finland, Madagascar, Australia, and the USA.