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Topic: Perthite

	perthite
		"Perthite" is an intergrowth of two different Feldspar minerals in one rock.
		Perthite is usually composed of veins or stripes of one Feldspar running through a different Feldspar.
		Microperthite - Perthite in which the feldspar intergrowth is very fine but it can be detected with an unaided eye.
	www.minerals.net /mineral/silicate/tecto/feldspar/variety/perthite.htm (165 words)

	GemRocks: Perthite
		Perthite beads and cabochons (larger one is the one in "A"), fashioned from perthite from the well-known Amelia Courthouse area, Virginia.
		-- only known to be perthitic on the basis of investigations utilizing procedures such as x-ray diffraction or electron microscopy; in some cases, however, identity as a crytoperthite may be surmised on the basis of the feldspar's having a moonstone appearance.
		The patterns assumed by the two feldspars in perthites are rather diverse; indeed, several perthites have been described, on the basis of the shapes of their albite constituent, by preceding the term perthite (etc.
	www.cst.cmich.edu /users/dietr1rv/perthite.htm (1122 words)

	NationMaster - Encyclopedia: Feldspar (Site not responding. Last check: )
		Perthite is a typical texture in alkali feldspar, due to exsolution of contrasting alkali feldspar compositions during cooling of an intermediate composition.
		The perthitic textures in the alkali feldspars of many granites are coarse enough to be visible to the naked eye.
		A perthite is a structural (perthitic structure) variety of the potassium feldspars microcline and orthoclase (KAlSi3O8).
	www.nationmaster.com /encyclopedia/Feldspar (1657 words)

	Lord Hill Pegmatite, Stoneham Maine
		Perthite content increases from the border zone inward, and the inner contact of the zone is drawn approximately at the place where perthite becomes the most abundant mineral (Pl. 1).
		The chief minerals of the core are perthite, quartz, muscovite, and cleavelandite, with minor amounts of albite, biotite, fluorite, spessartite(?), and topaz.
		Both cleavelandite and perthite replace, corrode, and vein the original core minerals and are thus later in age.
	www.minsocam.org /MSA/collectors_corner/arc/melordpeg.htm (5085 words)

	Definitions of Some of the More Common Petrographic Terms
		In perthite potash feldspar encloses plagioclase but in antiperthite plagioclase encloses potash feldspar.
		Perthitic - describing the intergrowth of potash feldspar and plagioclase.
		The texture may be due to replacement of host by included mineral, simultaneous crystallization of the two minerals (less probable), or the separation or unmixing from solid solution as a result of instability induced bycooling.
	neld.lib.uconn.edu /definitions.html (1682 words)

	Case
		Perthite crystals in the perthite-quartz intermediate zone are euhedral against quartz of the core.
		The zonal structure was clearly recognizable in 3 of the 4 drill holes that intersected the pegmatite 1, 2, and 5.
		On the basis of this figure, and diamond drilling, 53 tons of beryl are indicated and 27 tons are inferred to lie beneath the surface to a depth of 180 feet clown the dip.
	www.lmscc.org /case.htm (4507 words)

	Boaz Cohen's M.Sc. research page
		There are several kinds of textures caused by the albitic phase inside perthite crystals (one of the minerals found in granite rocks).
		Computerized classification of perthite images can help geologists distinguish between granitoid rocks and contribute to the understanding of the influence of various physical conditions on the development of the different perthite textures.
		The main contribution of the proposed system is that it is a fast and objective tool for perthite crystal texture classification and will enable a large scale research of the perthite texture aspect of granite rocks.
	www.ee.bgu.ac.il /~boazc/MSc.html (348 words)

	perthite
		Feldspars are complicate both in structure and in composition.
		Perthite is a representative mineral for the situation.
		Read information about perthite in the textbook and consider the following questions (a brief definition of antiperthite can be found on this web site):
	muskingum.edu /~ericlaw/pd_courses/geol301/exercise/perthite.html (142 words)

	Amazonite with Albite (Perthite) Cutting Rough
		This material is often called amazonite, but it is more properly called perthite, which is the combination of the minerals amazonite and perthite.
		The green-blue color is amazonite and the white to cream colored contrasting stripes are albite.
		We were lucky to be able to select some of the best out of a large parcel.
	www.greatrough.com /rough_amazonite_perthite.shtml (310 words)

	MICROCLINE (Potassium Aluminum Silicate)
		Amazonite is a variety that is deep green and is suitable for carving and polishing.
		The perthite variety is a stripped, veined or almost zebra patterened stone, that is produced from lamellar intergrowths inside the crystal.
		Perthite intergrowths causes a stripped appearance is some specimens.
	mineral.galleries.com /minerals/silicate/microcli/microcli.htm (551 words)

	Magmatic and Postmagmatic Processes in Tin-mineralized Granites: Topaz-bearing Leucogranite in the Eurajoki Rapakivi ...
		The alkali feldspar is usually perthitic (string, vein and patch perthite), whereas in strongly recrystallized granite it may be nearly homogeneous K-feldspar.
		Sometimes, the albite rim has as remnants inclusions of perthite albite (different orientation), which indicates that the formation of some perthite albite preceded the formation of rim albite in that zone.
		A schematic model of the progressive evolution of the perthite textures and the intergranular albite in the topaz-bearing granite of the Eurajoki stock.
	www.oxfordjournals.org /our_journals/petroj/online/Volume_38/Issue_12/html/ega083_gml.html (6482 words)

	Zapot pegmatite mineral county, The Mineralogical Record - Find Articles
		The earliest and most extensive zone of the pegmatite is in contact with the quartz monzonite phase of the batholith and is in intrusive contact with limestones of the Luning Formation.
		Amazonite-smoky quartz-topaz veins cut the perthite zone and near-vertical lenses (1-3 cm wide by 1-5 cm long) occupy a zone up to 40 cm wide adjacent to the amazonite-smoky quartz-topaz zone.
		This is the outermost of the main zones, and formed at the contact with the host quartz monzonite and the perthite zone.
	www.findarticles.com /p/articles/mi_qa3672/is_199907/ai_n8875608/pg_3 (581 words)

	Perthite (Site not responding. Last check: )
		A perthite is a structural (perthitic structure) variety of the Potassium feldspars Microcline and Orthoclase (KAlSi
		It usually manifests itself in the form of a series of perpendicular vertical and horizontal lines, giving it a woven or cross hatched appearance under the petrographic microscope.
		It is licensed under the GNU free documentation license.
	www.ufaqs.com /wiki/en/pe/Perthite.htm (146 words)

	Kanspar Industries Inc. - Geology of the Barriere Feldspar Property - The Barriere feldspar composition is within ... (Site not responding. Last check: )
		Bedrock samples indicate a “perthite feldspar”; and a mineral assemblage of orthoclase, microcline and albite.
		The coarse porphyry crystals of perthite (orthoclase - microcline - albite) feldspar co-exist with low iron oxide and minor accessory mineral contaminants.
		The Barriere feldspar composition is within commercial specifications and is classified as massive perthite in the orthoclase - microcline - albite range, or Potash Spar.
	www.kanspar.com /geology.html (819 words)

	Mt. Rogers Formation
		Rankin describes the Fees Rhyolite as containing approximately 35% phenocrysts composed of quartz, perthite, and plagioclase, with the presence of both plagioclase and quartz phenocrysts distinguishing these rhyolites from the younger main Mount Rogers rhyolites.
		The conglomerate of the lower part of the Mount Rogers Formation as found at Stop 1 of the Mount Rogers Trip, on Rt.
		The few phenocrysts that are present are quartz and perthite.
	www.runet.edu /~fldsch/RUFieldschool/formationpages/Mt.%20Rogers%20Fm/MtRogers.html (972 words)

	Kanspar Industries Inc. - Geology of the Barriere Feldspar Property - The Barriere feldspar composition is within ... (Site not responding. Last check: )
		Bedrock samples indicate a “perthite feldspar”; and a mineral assemblage of orthoclase, microcline and albite.
		The coarse porphyry crystals of perthite (orthoclase - microcline - albite) feldspar co-exist with low iron oxide and minor accessory mineral contaminants.
		The Barriere feldspar composition is within commercial specifications and is classified as massive perthite in the orthoclase - microcline - albite range, or Potash Spar.
	kanspar.com /geology.html (819 words)

	The Baringer Hill, Texas, Pegmatite
		The feldspar is a microcline-albite perthite, with the albite decidedly subordinate.
		The microcline is visibly perthitic and the percentage of albite is materially greater than in the graphic granite microcline.
		The writer believes that this transverse albite is older albite which was present in the microcline perthite of the normal pegmatite, and that the tabular albite has replaced the perthite to such an extent that the original microcline has almost disappeared.
	home.satx.rr.com /robnjean/bh/landes1.html (2735 words)

	Perthite: Perthite mineral information and data.
		Brown, W.L. and Parsons, I. (1984) The nature of potasssium feldspar, exsolution microtextures and development of dislocations as a function of composition in perthitic alkali feldspars.
		Worden, R.H., Walker, F.D.L., Parsons, I., and Brown, W.L. (1990) Development of microporosity, diffusion channels and deuteric coarsening in perthitic alkali feldspars.
		Waldron, K.A., Lee, M.R., and Parsons, I. (1994) The microstructure of perthitic alkali feldspars revealed by hydrofluoric acid etching.
	www.mindat.org /min-6683.html (266 words)

	MYRMEKITE 42 of 50
		Perthite and micrographic textures show characteristics of magmatic origin, but myrmekite and tourmaline-microcline intergrowth probably have metasomatic origin.
		Myrmekite is an intergrowth of vermicular quartz and sodic plagioclase which occurs near the rim of a plagioclase crystal, either between grains of perthitic K-feldspar or along the contact of K-feldspar and plagioclase crystals (Turner and Verhoogen, 1960, p.
		Perthite is an intergrowth of a daughter (guest) Na-rich plagioclase (albite or oligoclase) in a parent (host) K-rich feldspar (orthoclase or microcline), which can be introduced by exsolution (unmixing) or replacement (metasomatism) due to reactions between permeating fluids and primary feldspar (Moorhouse, 1959, p.
	www.csun.edu /~vcgeo005/Alvand.htm (1324 words)

	MICROCLINE (Potassium Aluminum Silicate)
		Amazonite is a variety that is deep green and is suitable for carving and polishing.
		The perthite variety is a stripped, veined or almost zebra patterened stone, that is produced from lamellar intergrowths inside the crystal.
		Perthite intergrowths causes a stripped appearance is some specimens.
	www.galleries.com /minerals/silicate/microcli/microcli.htm (551 words)

	IngentaConnect Thermoluminescence of the blue emission band of perthite
		The thermoluminescence (TL) glow curve of natural monoclinic perthite has a broad band with peaks at 210, 250, 290 and 340 °C in the blue region.
		4 times of that annealed at 400 °C. Thermoluminescence fading of the disordered perthite was monitored six months after storage in the dark at room temperature.
		The results show that perthite is a promising material for dosimetry of luminescence dating.
	www.ingentaconnect.com /content/tandf/grad/2004/00000159/00000002/art00005 (194 words)

	PERTHITE Articles Perthite is used to describe an int
		PERTHITE Articles Perthite is used to describe an int
		Perthite is used to describe an intergrowth of two feldspars a host grain of potassium-rich alkali feldspar (near K-feldspar, KAlSi
		The gem varieties of potassium feldspar, amazonite and moonstone are variant colored perthites.
	www.amazines.com /Perthite_related.html (422 words)

	Perthite
		The microcline has tartan twinning, while the albite is the globular gray areas.
		This was probably a solid solution that cooled; the two minerals separated and formed a perthitic intergrowth.
		Perthite in plane polarized light, click to go to rollover link, so you can view it in plane polarized light and crossed polarized light
	www.science.smith.edu /departments/Geology/Petrology/Petrography/Perthite/Perthite.html (245 words)

	News \| Gainesville.com \| The Gainesville Sun \| Gainesville, Fla. (Site not responding. Last check: )
		Perthite is used to describe an intergrowth of two feldspars: a host grain of potassium-rich alkali feldspar (near K-feldspar, KAlSi
		The intergrowths in perthite have a great variety of shapes.
		The gem varieties of potassium feldspar, amazonite and moonstone are variant colored perthites.
	www.gainesville.com /apps/pbcs.dll/section?category=NEWS&template=wiki&text=Perthite (231 words)

	TEXTURES REFERRING TO INTERGROWTH (Site not responding. Last check: )
		Whatever the orientation in thin section, the albite component always has the higher birefringence and appears brighter under crossed nicols, a useful feature in identification, as the exsolution lamellae are generally far too small to show any diagnostic multiple twinning.
		Exsolution of albite patches in microcline crystal to form perthitic texture.
		refers to the typical perthite of epizone granitic bodies wherein the albite component is comparable in abundance to the orthoclase component may come to form an anastomosing host around remnants of an orthoclase component (generally still relatively more abundant).
	www.metu.edu.tr /home/www64/geoweb/igneous-intergrowth.htm (656 words)

	[No title]
		Aegirine, astrophyllite, bastnaesite, biotite, fluorite, hornblende grp., ixiolite, monazite, muscovite, perthite, phenakite, pyroexene grp., quartz, riebeckite, uranothorite, xenotime, zircon.
		Aegirine, amphibole grp., analcime, apatite grp., barite, biotite, calcite, cancrinite, chalcopyrite, chlorite, grp., diopsiide, dolomite, fluorite, garnet grp., hematite, kaersutite, magnetite, muscovite (sericite), nepheline, olivine, perthite, pyrite, pyroxene grp., pyrrhotite.
		Aegirine, aenigmatite, albite, amphbole grp., apatite grp., arfvedsonite, astrophyllite, catapleiite, eudialyte, ferro-omphacite, fluorite, innelite, jadeite, joaquinite, karnasurtite, lamprophyllite, Ti-lavenite (normandite ??), microcline, nepheline, neptunite, niobophyllite, pectolite, perthite, quartz, ramsayite, riebeckite, titanite, vinogradovite, zircon.
	www.koeln.netsurf.de /~w.steffens/can.htm (2311 words)

	Mineral Land Rocks (Site not responding. Last check: )
		The Jasper referred to in the Bible was probably a dark green or opalescent stone.
		This specimen is from Canada, but Perthite is found also in Brazil and the United States.
		Perthite is often pink, red, or honey colored.
	www.keeline.com /MineTrain/MineralHall/MineralLandRocks.html (203 words)

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