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Feldspar is mined from large granite bodies (called plutons by geologists), from pegmatites (formed when the last fluid stages of a crystallizing granite becomes concentrated in small liquid and vapor-rich pockets that allow the growth of extremely large crystals), and from sands composed mostly of feldspar.
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www.mii.org/Minerals/photofelds.html
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One of these elements is usually dominant, but most of the feldspars contain all 3 in varying amounts. It is the proportions of these 3 elements which help determine which specific feldspar is formed. The feldspars are divided into 2 broad categories: plagioclase, which contains calcium and sodium;
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jersey.uoregon.edu/~mstrick/AskGeoMan/geoQuerry34.html
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Feldspar is an orthoclase, which means that it forms around volcanic and hydrothermal deposits. Feldspar is generally found in pegmatites. These are masses of rock that contain unusually large quantities of feldspar, quartz and mica. Pegmat...
http://www.ehow.com/how-does_4968624_how-moonstones-for...
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In 1995, tests on several granitic plutons (igneous rock formed below the earth's surface) indicated that the Churchland pluton and the Rolesville granite in the Raleigh Belt contain high concentrations of potassium (K) feldspar (Carpenter, Schlanz and Carpenter, 1995). The Churchland pluton is located in central...
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www.geology.enr.state.nc.us/Mineral%20resources/feldmod...
www.geology.enr.state.nc.us/Mineral%20resources/feldmod.html
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Sunstone is a species of plagioclase called "oligoclase" or known sometimes in the jewelry industry as "adventurine feldspar". It gets is shiller in the same way that labradorite does, but the background color is brown to orange, and the composition is full of small hematite crystals that give it additional sparkle.
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www.theimage.com/gemstone/feldspar/feldspar.html
www.theimage.com/gemstone/feldspar/feldspar.html
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One example of the feldspar class of minerals is orthoclase. The other feldspar mineral is called "plagioclase". ... There are many different minerals which make up the rocks of which the planets are formed.
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www.windows.ucar.edu/earth_science/geology/rocks/feldsp...
www.windows.ucar.edu/earth_science/geology/rocks/feldspar.html
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Feldspar - The Different Colors, Shapes, and Sizes ... How and where is Feldspar formed and found? ... In fact, moonstone is not a gemstone or even a fancy mineral, it comes from Feldspar. Feldspar is so common, that it makes up almost 60% of the earth’s crust. While Feldspar is extremely common, moonstone which is found...
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www.gemstoneeducation.com/Feldspar.htm
www.gemstoneeducation.com/Feldspar.htm
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The presence of halite daughter crystals in breached fluid inclusions, low whole-rock ratios of chlorine to bromine, and thermochemical data suggest that the potassium feldspar formed at low temperature by the reaction of connate brines with intercalated siliciclastic debris.
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www.sciencemag.org/cgi/content/abstract/228/4707/1529
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are comprised of the mineral feldspar and were formed through volcanic action. Feldspar crystals are found in several locations throughout the globe. The pink schiller, red, bi-colored and green varieties are currently found only in Oregon.
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