Labradorite

labradorite (lăb`rədôrīt', lăbrədôr`īt), a variety of plagioclase feldspar.

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labradorite

Type of feldspar mineral in the plagioclase series that is often valued as a gemstone and as ornamental material for its red, blue, or green iridescence. The mineral is usually gray or brown to black and need not be iridescent. Labradorite is named for its occurrence on the coast of Labrador, Canada.

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labradorite [′lab·rə‚dȯ‚rīt]

(mineralogy)

A gray, blue, green, or brown plagioclase feldspar with composition ranging from Ab₅₀An₅₀to Ab₃₀An₇₀, where Ab = NaAlSi₃O₈and An = CaAl₂Si₂O₈; in the course of formation when the natural material cools, the feldspar sometimes exhibits a variously colored luster. Also known as Labrador spar.

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Labradorite 

(named for a deposit on Labrador), a mineral of the soda-lime feldspars—the plagioclases. It is an isomorphic mixture of soda feldspar (albite) with lime feldspar (anorthite). The mineral contains 50–70 percent anorthite. It crystallizes in the triclinic system; it is colorless, white, or gray and forms complex twins, often with an attractive blue-green and golden iridescence. Its hardness is 6 on the Mohs’ scale and its density is 2,680–2,720 kg/m³. Labradorite enters into the composition of many basic magmatic rocks, including gabbros, basalts, and diabases. Rocks consisting almost entirely of labradorite are called labradoritites.