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

Labradorite

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

Hardness: 6.0-6.5 Mohs; Color: Gray to black with labradorescence (blue, green, gold); Luster: Vitreous to pearly; Crystal structure: Triclinic; Cleavage: Two directions at nearly 90 degrees; Specific gravity: 2.68-2.72.

Hardness
6
Color
Gray to black with labradorescence (blue, green, gold)
Luster
Vitreous to pearly
Identified More mineral

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Physical properties

Hardness: 6.0-6.5 Mohs; Color: Gray to black with labradorescence (blue, green, gold); Luster: Vitreous to pearly; Crystal structure: Triclinic; Cleavage: Two directions at nearly 90 degrees; Specific gravity: 2.68-2.72.

Formation & geological history

Forms in mafic igneous rocks like basalt and gabbro, as well as in anorthosite. It crystallizes from cooling magma in deep crustal environments and is famously part of the Precambrian Paul's Island deposit in Labrador, Canada.

Uses & applications

Primarily used as a gemstone for jewelry, ornamental carvings, and high-end architectural stone (countertops/tiles). Also collected as a metaphysical stone and mineral specimen.

Geological facts

The iridescent effect is known as 'labradorescence,' caused by light diffracting between microscopic layers of different feldspar compositions. It was first discovered in Labrador, Canada, in 1770.

Field identification & locations

Identify it by its dark ground color and the 'flash' of iridescent color when tilted under light. Commonly found in Canada, Madagascar, and Finland (where a high-quality variety called Spectrolite is mined).