LABRADORITE

Labradorite

Labradorite, a feldspar mineral, is an intermediate to calcic member of the plagioclase series. It is usually defined as having "%An" between 50 and 70. The specific gravity ranges from 2.68 to 2.72. The streak is white, like most silicates. The refractive index ranges from 1.559 to 1.573. Twinning is common. As with all plagioclase members the crystal system is triclinic and three directions of cleavage are present two of which form nearly right angle prisms. It occurs as clear, white to gray, blocky to lath shaped grains in common mafic igneous rocks such as basalt and gabbro, as well as in anorthosites.

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labradorite

Noun

  1. A plagioclase feldspar mineral, calcium sodium aluminum silicate, often very coarsely crystalline, used as a decorative stone for carvings and building facades.


The above text is a snippet from Wiktionary: labradorite
and as such is available under the Creative Commons Attribution/Share-Alike License.

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