labradorite


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labradorite

(lăb`rədôrīt', lăbrədôr`īt), a variety of plagioclase feldsparfeldspar
or felspar
, an abundant group of rock-forming minerals which constitute 60% of the earth's crust. Chemically the feldspars are silicates of aluminum, containing sodium, potassium, iron, calcium, or barium or combinations of these elements.
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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.

labradorite

[′lab·rə‚dȯ‚rīt]
(mineralogy)
A gray, blue, green, or brown plagioclase feldspar with composition ranging from Ab50 An50 to Ab30 An70, where Ab = NaAlSi3O8 and 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.
References in periodicals archive ?
It is coarse-grained, grey, black or bluish-black with an ofitic texture, and contains labradorite with iridescent colours used as gemstone ("spectrolite").
This lovely chunky moonstone, labradorite and turquoise bracelet (above) from John Lewis is pounds 75.
Rubies, emeralds, sapphires, topaz, fire opal, garnet, tourmaline, labradorite, moonstone, and my own current favourite, black star obsidian, are just a few of the stones available, all set in silver.
Labradorite is named for Labrador, where it was first discovered.
Bainbridge identifies a number of pieces as being his work, including a grey chalcedony donkey in the Royal Collection and a labradorite owl given by Queen Alexandra to her friend Lady De Grey, the Marchioness of Ripon.
The core composition for all three types of crystals, as determined mainly by extinction angle methods, is bytownite for units A, C, E and G; labradorite for unit B and oligoclase for unit D.
Rubies, emeralds, sapphires, topaz, fire opal, garnet, tourmaline, labradorite, moonstone, and black star obsidian, are just a few of the stones available, all set in silver.
Its range includes: Cappuccino Mocha, Magma Gold, Blue Pearl, Eucalyptus, Alpine Green, Crema San Marco, Verde Fantastic, Juprana Exotica, Indian Green Labradorite and Golden Teak Quartzite.
Intaglio talisman necklace, $360; Bangles with semi precious stones, $602 each; Yellow sterling silver pearl necklace wtih labradorite beads and round zircons, $259
She uses gemstones, such as tourmaline, labradorite, moonstone, chalcedony, turquoise and aventurine, which are reminiscent of sea glass.