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Topic: Feldspar

	AllRefer.com - feldspar, Mineral (Mineralogy And Crystallography) - Encyclopedia
		Feldspar is found in association with all rock types, including granite, gneiss, basalt, and other crystalline rocks, and are essential constituents of most igneous rocks.
		Feldspars weather to yield a large part of the clay found in soils.
		Feldspar crystals are either monoclinic or triclinic (see crystal), and all show clean cleavage planes in two directions.
	reference.allrefer.com /encyclopedia/F/feldspar.html (342 words)

	THE FELDSPAR GROUP OF MINERALS
		The feldspars are a group of minerals that have similar characteristics due to a similar structure.
		The plagioclase feldspars are a set of minerals that are in a series from a sodium rich end member, albite, to a calcium rich end member, anorthite.
		Once identified, however, some feldspar mineral varieties are found to have distinctive characteristics or originate from a classic locality and on these bases are recognized by mineral collectors as belonging to a specific feldspar mineral.
	mineral.galleries.com /minerals/silicate/feldspar.htm (446 words)

	Feldspar (Site not responding. Last check: 2007-10-05)
		Feldspar is a name given to a class of aluminum-containing silicates which form with no cleavage planes.
		This feldspar is distinguished from the orthoclase form by its content of calcium and sodium.
		This feldspar is distinguished from the plagioclase form by its content of potassium.
	230nsc1.phy-astr.gsu.edu /hbase/geophys/feldspar.html (481 words)

	Feldspar - Wikipedia, the free encyclopedia
		Feldspar is the name of an important group of rock-forming minerals which make up perhaps as much as 60% of the Earth's crust.
		Feldspars crystallize from magma in both intrusive and extrusive rocks; they occur as compact minerals, as veins, and are also present in many types of metamorphic rock.
		Feldspars are also found in many types of sedimentary rock.
	en.wikipedia.org /wiki/Feldspar (144 words)

	Orthoclase, rock, crystal, mineral, gem stone, birth stones - mineralgallery
		Feldspars are used in the manufacture of ceramics and ceramic glazes and as mild abrasives.
		Feldspars are also major constituents of moon rocks, which are similar to rocks of the Earth's crust.
		The high-temperature potassium feldspars, sanidine and orthoclase, are monoclinic in their crystal symmetry; the others are triclinic, although they retain the general atomic pattern of the monoclinic species.
	www.mineralgallery.co.za /orthoclase.htm (682 words)

	PIRSA Minerals - Mineral Resource Potential - Feldspar (Site not responding. Last check: 2007-10-05)
		Feldspars are aluminosilicate minerals with varying amounts of potassium, sodium and calcium in a solid solution series.
		Most commercial varieties are alkali feldspars, with composition between sodium and potassium end members, or at the sodic end of the plagioclase (sodium—calcium) group.
		From 1986 to 1989, 14 800 t of feldspar were mined from a partly kaolinised quartz—feldspar—muscovite pegmatite near the western margin of the Mount Crawford kaolinite—sillimanite orebody during a phase of quarry expansion.
	www.pir.sa.gov.au /pages/minerals/commodity/feldspar.htm:sectID=245&tempID=7 (462 words)

	kittikornmining
		Chemically the feldspars are silicates of aluminum, containing sodium, potassium, iron,calcium, or barium or combinations of these elements.
		Feldspar is found in association with all rock types, including granite, gneiss, basalt, and other crystalline rocks, and are essential constituents of most ingeous rocks.
		Feldspar crystals are either monoclinic or triclinic and all show clean cleavage planes in two directions.
	www.kittikornmining.homestead.com /index1.html (368 words)

	Information about Feldspar and Moonstones (Site not responding. Last check: 2007-10-05)
		Moonstone is the name given to the member of feldspar group that displays a sheen effect (adularescence or schiller).
		The sheen effect is caused by the intergrowth of two different types of feldspar with different refractive indexes: These intergrowths result from compatible chemistries at high temperatures becoming incompatible at lower temperatures and thus a separating and layering of these two phases when the stone cools down during its genesis.
		Feldspar is the group name applied to several crystalline aluminosilicate minerals that are found in abundance in the earth's crust in many localities throughout the world, especially in pegmatites.
	www.gemwow.com /category_info.php?cat1=133&cat2=312 (371 words)

	Feldspar - SmartyBrain Encyclopedia and Dictionary
		Feldspar (from the German Feld, field, and Spat, a rock that does not contain ore) is the name of an important group of rock-forming minerals which make up perhaps as much as 60% of the Earth's crust.
		This group of minerals consists of three silicates: a potassium-aluminium silicate (the orthoclase feldspars), a sodium-aluminium silicate, and a calcium-aluminium silicate (the plagioclase feldspars) and their isomorphous mixtures.
		Labradorite is the characteristic feldspar of the more basic rock types such as diorite, gabbro, andesite or basalt and is usually associated with one of the pyroxenes or amphiboles.
	smartybrain.com /index.php/Feldspar (678 words)

	Astrology & Gemstones, Birthstones: Feldspar Gemstone - Gems shop
		The name "feldspar" comes from "field stone", because when feldspar weathers, it releases large amounts of plant nutrients, such as potassium, which enrich the soil.
		Feldspar minerals are aluminum silicates of either potassium, sodium, and calcium.
		Feldspars are a family of minerals that include moonstone (adularia), amazonite, sunstone, and labradorite.
	www.findyourfate.com /gemology/gemstones/Feldspar.html (219 words)

	Journal of the Geological Society: Systematic destruction of K-feldspar in deeply buried rift and passive margin ... (Site not responding. Last check: 2007-10-05)
		Feldspar is the most abundant unstable detrital mineral within rift and passive margin basins (Dickinson & Suczek 1979), the fate of which during burial is hotly debated, and has both academic and economic implications.
		However, if feldspar dissolves during burial and the products are exported from the host sandstone, then the deeply buried sandstone may change its bulk composition, and economically important secondary pore space may be created, partially replacing the primary porosity lost by physical compaction.
		This demonstrates that feldspar dissolution is an important process in the deep subsurface, and is not restricted to shallow depths with high fluxes of meteoric water.
	www.findarticles.com /p/articles/mi_qa3721/is_200107/ai_n8956707 (1272 words)

	Bob's Rock Shop: Feldspar
		Minerals in the feldspar group are found in many places throughout the world, in pegmatites, even meteorites, and pass through all rock and ore-forming processes: igneous, metamorphic, hydrothermal and sedimentary, yet only rarely do they occur as gemstones.
		Feldspars are the most diversified and the most extensively investigated minerals on earth, though they only recently commanded the attention they deserve.
		Feldspar, in all its chemical compositions, habits and colors, is a fascinating mineral group to study and collect.
	www.rockhounds.com /rockshop/feldspar.html (1771 words)

	Mineral Information Institute - FELDSPAR
		Feldspar: A rock-forming mineral, industrially important in glass and ceramic industries, pottery and enamelware, soaps, abrasives, bond for abrasive wheels, cements and concretes, insulating compositions, fertilizer, poultry grit, tarred roofing materials, and as a sizing (or filler) in textiles and paper.
		Albite is a feldspar mineral and is a sodium aluminum silicate.
		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.
	www.mii.org /Minerals/photofelds.html (532 words)

	USGS SET website - Establishing Marker Horizons
		Brick dust, Grog, Sand, Kaolin, glitter and varieties of feldspar clay are all suitable for marker horizons.
		If you are laying feldspar in a pond or on a flooded marsh, we use trash cans with the bottom cut off to define the feldspar plot and aid in establishing the horizon.
		Be sure to draw a map in your data book showing the relative locations of the feldspar plots in case the PVC stakes are lost.
	www.pwrc.usgs.gov /set/installation/markers.html (645 words)

	Kanspar Industries Inc. - Barriere Feldspar Property, a source of potash in the Interior of British Columbia (Site not responding. Last check: 2007-10-05)
		The Barriere Feldspar Property is located in the Interior of British Columbia, near the town of Barriere, 60 km north of Kamloops, and is accessible by British Columbia Forest Service road from Barriere.
		Feldspar consumers located in Western Canada and the northwestern United States are prime markets for a potential of 20,000 tons/year.
		The Barriere feldspar property is well-positioned to supply a market for processed feldspar in British Columbia and elsewhere in Western Canada and the United States.
	www.kanspar.com (398 words)

	Feldspar Structure
		Below is a view of feldspar in the (010) plane, along the b-axis, with the a- and c-axis directions shown.
		The feldspars have cleavage along (001), that is, the vertical plane between the chains, and (010), the mirror planes between the double layers.
		The radii of the principal feldspar cations in Angstrom units are: K 1.6; Ba 1.5; Na 1.4 and Ca 1.25.
	www.uwsp.edu /geo/projects/geoweb/participants/dutch/petrolgy/FeldsparStruct.HTM (1033 words)

	Feldspar - Gemstone Information
		Feldspar is a group of minerals which are important in the formation of many rocks.
		There are a few gem varieties of feldspar, the most important of which is moonstone.
		All feldspars are types of aluminium silicate, with potassium, calcium, sodium or barium.
	www.24carat.co.uk /feldspar.html (223 words)

	Microstructures: Naturally deformed quartzofeldspathic rocks (Site not responding. Last check: 2007-10-05)
		Feldspar is present as clasts only, fractured but not showing any traces of dynamic recrystallization.
		The layers of recrystallized feldspar are clearly derived from the progressive deformation of large feldspar porphyroclats; the recrystallized feldspar aggregate is concentrated in the pressure shadows of large grains and strung out to form the mylonitic foliation.
		Feldspar porphyroclast in ultramylonite showing asymmetric tails of recrystallized feldspar as well as asymmetric concentration of white mica on the NW and SE sides of the grain (bright domains).
	www.geo.umn.edu /orgs/struct/microstructure/sec6.html (875 words)

	Clastic Sedimentary Rock Classification
		Feldspars are some of the most abundant minerals in the earth's crust.
		Sediments near high mountains frequently have large percentages of feldspar as batholiths and regional metamorphic rocks are uplifted and eroded (Wilson Cycle Stage F and Stage H).
		Feldspars, on the other hand, have cleavage faces (quartz has no cleavage) that can sometimes be seen with careful looking, such as in Ca plagioclase, Na plagioclase, and orthoclase.
	csmres.jmu.edu /geollab/Fichter/SedRx/Clastic.html (1862 words)

	Feldspar
		Feldspar is by far the most abundant group of minerals in the earth's crust, forming about 60% of terrestrial rocks.
		Feldspar minerals are essential components in igneous, metamorphic and sedimentary rocks, to such an extent that the classification of a number of rocks is based upon feldspar content.
		Feldspars are used as fluxing agents to form a glassy phase at low temperatures and as a source of alkalies and alumina in glazes.
	www.ima-na.org /about_industrial_minerals/feldspar.asp (593 words)

	Feldspar (Site not responding. Last check: 2007-10-05)
		The plagioclase feldspars represent the "continuous branch" of Bowen's Reaction Series, and form a complete series between anorthite (the pure calcium member), and albite (the sodium-rich variety).
		I once saw an estimate that said that 60% of the earth's crust is composed of feldspar.
		This is quite a number, and since feldspar is nearly always present in igneous rocks, most classification schemes depend on the amount and kind of feldspar.
	jersey.uoregon.edu /~mstrick/AskGeoMan/geoQuerry34.html (387 words)

	PEGMATITE-CONTAINING SHEAR ZONES: A MECHANISM FOR THE FORMATION OF LARGE ISOLATED FELDSPAR AUGEN (Site not responding. Last check: 2007-10-05)
		This mechanism of forming isolated feldspar augen is documented by pegmatites that underwent extension and thinning under amphibolite facies conditions in a low angle ductile normal fault at the basement-cover contact of the Willimantic dome, eastern Connecticut.
		Intact pegmatites containing large feldspar augen surrounded by recrystallized pegmatite gradually disassociate forming strands of floating feldspar augen, connected by very thin layers of recrystallized quartzo-feldspathic material parallel to the dominant foliation.
		Feldspar grains within single sheared pegmatite strands vary dramatically in their degree of deformation and recrystallization.
	gsa.confex.com /gsa/2001AM/finalprogram/abstract_24631.htm (446 words)

	Olivine, Cordierite and Feldspar (Site not responding. Last check: 2007-10-05)
		Feldspars are the most abundant minerals in the Earth"s crust.
		Feldspars are very important rock-forming minerals and they are covered in more detail in other geology courses.
		Sunstone and Aventurine have inclusions of Cu in the feldspar
	ist-socrates.berkeley.edu /~eps2/wisc/Lect14.html (425 words)

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