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Topic: Pegmatite

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	Earlham College - Geology 211 - Template
		Pegmatites are coarse grained, generally igneous mineral deposits which result from disparate rates of cooling within a trapped pocket of magma, possibly due to volitiles which remain after the rest of the pluton has crystallized.
		Unzoned pegmatites are generally formed through replacement or recrystallization of the wall rock rather than crystallization out of a fluid and therefore lack the diversity of minerals or the complexity of structure seen in zoned pegmatites.
		Unzoned pegmatites are generally less influenced by hydrothermal factors than the zoned are, which explains in part the lesser mobility of ions which inhibits their ability to crystallize into distinct zones.
	www.earlham.edu /~stanlwi/Webs/pegmatites.htm (800 words)

	Pegmatite: World of Earth Science
		A pegmatite may be a segregation within an associated plutonic rock or a dike or vein that intrudes the surrounding country rock.
		The composition range of pegmatites is similar to that of other intrusive igneous rocks and is indicated by using modifier, e.g., granite pegmatite or gabbro pegmatite.
		Pegmatites are also valued for the suite of rare elements that tend to be concentrated in the residual magmas.
	science.enotes.com /earth-science/pegmatite (382 words)

	Kids.Net.Au - Encyclopedia > Pegmatite
		Pegmatite is a very coarse-grained igneous rock having a grain size of 20 mm or more; such rocks are referred to as pegmatitic.
		Most pegmatites are granite with quartz, feldspar, and mica.
		Pegmatites are important because they often contain other rare earth minerals and gemstones, such as aquamarine, tourmaline, topaz, fluorite, apatite, tin, and tungsten, among others.
	www.kids.net.au /encyclopedia-wiki/pe/Pegmatite (94 words)

	THE SYENITE PEGMATITES
		Syenite pegmatite dikes are encountered throughout the whole Larvik plutonic complex and in the basaltic rocks close to the border.
		The main pegmatite minerals on Låven are white microcline, reddish to brownish nepheline, grey sodalite, aegirine-augite, biotite and magnetite.
		The Vøra pegmatite dikes are situated in the western slope of a steep cliff (Husefjellet) immediately east of the entrance of Vøra Camping on Vesterøya, approximately 8 km south-south-east of Sandefjord.
	home.c2i.net /aolarsen/Pegmatites.htm (2112 words)

	Igneous Rock: Pegmatite - Picture - MSN Encarta
		Pegmatite is a variety of igneous rock with extremely large crystals; individual crystals can be as large as a bathtub.
		Pegmatites are the last rocks to crystallize from a solidifying body of magma.
		The slow rate of cooling and the presence of large amounts of water dissolved in the magma account for the large size of the crystals.
	encarta.msn.com /media_461569345/Igneous_Rock_Pegmatite.html (66 words)

	Geology of Mount Blue State Park - Objects of Interest - Maine Geological Survey
		The outcrops of pegmatite show a feature known as sheeting, which is a set of joints, or fractures, having a low angle of dip.
		The former mentioned pegmatite is nearly parallel to the bedding in the metamorphic rock, and thus can almost be called a sill, this latter one very definitely cuts across the bedding (see Figure 8).
		The pegmatite is composed of quartz and feldspar.
	www.maine.gov /doc/nrimc/mgs/explore/bedrock/mt-blue/objects.htm (1702 words)

	PEGMATITE,
		The mineral constituents of pegmatite are largely those typical of acidic intrusive rocks: orthoclase feldspar, quartz, and mica.
		The growth of crystals this large indicates that the parent magma, from which the rock solidified, was able to cool very slowly, after injection into fissures extending outward from a central magma chamber.
		Pegmatite is widely distributed in the crust of the earth but is found especially in older mountain chains, where it is restricted essentially to those surface areas in which igneous and metamorphic rocks are prevalent.
	www.history.com /encyclopedia.do?vendorId=FWNE.fw..pe038600.a (192 words)

	Aplite and Pegmatite Dikes – Anza Borrego SP - Earthcaches on Waymarking.com (Site not responding. Last check: )
		Aplite and Pegmatite Dikes – Anza Borrego SP - Earthcaches on Waymarking.com
		Pegmatite grains are at least 20mm (by definition) and have been known to reach 32 feet (10 meters) long.
		Pegmatites are often contain rare earth minerals such as columbite and tantalite as well as gemstones and well formed crystals.
	www.waymarking.com /wm/WM5TG (673 words)

	Lee A. Groat - Pegmatite Research
		Granitic pegmatites host a diversity of rare mineral species, and are a globally important source of gemstones such as topaz, aquamarine, tourmaline and emerald.
		Granitic pegmatites are of importance in relative and absolute dating of the late stages of tectonic events.
		The pegmatite research is being done in collaboration with T. Mulja (UBC/MRG) and T.S. Ercit and R.A. Gault of the Canadian Museum of Nature.
	www.geology.ubc.ca /personal/groat/pegmatites.htm (748 words)

	Lee A. Groat - Pegmatite Research
		Granitic pegmatites host a diversity of rare mineral species, and are a globally important source of gemstones such as topaz, aquamarine, tourmaline and emerald.
		Granitic pegmatites are of importance in relative and absolute dating of the late stages of tectonic events.
		The pegmatite research is being done in collaboration with T. Mulja (UBC/MRG) and T.S. Ercit and R.A. Gault of the Canadian Museum of Nature.
	www.eos.ubc.ca /personal/groat/pegmatites.htm (748 words)

	Barringer Hill Pegmatite, Texas
		The minerals of the normal pegmatite, microcline and quartz, are of course of greatest quantitative importance.
		Where the normal pegmatite lies in contact with the red rock the border between the two is a replacive one with quartz and microcline the host minerals (Fig.
		The earlier quartz is that of the normal pegmatite and the peripheral graphic granite, while the later quartz occurs in the red rock and in crystals in cavities.
	www.minsocam.org /msa/collectors_corner/arc/barringertx.htm (2757 words)

	CVO Website - Pegmatite (Site not responding. Last check: )
		A pegmatite is an exceptionally coarse-grained intrusive igneous rock with large interlocking crystals (usually > one inch), typically forming as masses in dikes and veins, especially along the margins of batholiths.
		A granitic pegmatite has the mineralogy of a granite and abnormally large grains, whereas a gabbroic pegmatite has the mineralogy of a gabbro and very large grains.
		Pegmatites represent the last and most hydrous magma to crystallize, and sometimes contain rare minerals enriched in the elements boron, lithium, uranium, and rare earths.
	vulcan.wr.usgs.gov /LivingWith/VolcanicPast/Notes/pegmatite.html (130 words)

	Lee A. Groat - Pegmatite Research - Little Nahanni
		The spodumene-bearing pegmatites display a homogeneous mineral fabric and a rhythmic banding; the latter is defined by the distribution of the spodumene crystals and/or quartz.
		The absence of tourmaline (except at exocontacts) indicates that the pegmatites are poor in B. Analyses of the feldspars and micas indicate that the Group is highly evolved in terms of K-Rb systematics.
		The former is interpreted to be the emplacement date for the pegmatites and the latter are interpreted to be the timing of a thermal event responsible for resetting the K-Ar mica system.
	www.eos.ubc.ca /personal/groat/littlenahanni.htm (692 words)

	Zapot pegmatite mineral county, The Mineralogical Record - Find Articles
		The pegmatite is shaped somewhat like a tadpole with a 1 to 3-meter-wide tail extending northeasterly for about 35 meters and a "head" on the southwestern end which is exposed over an area measuring about 18 x 15 meters and a vertical depth of 6 meters.
		Dimensions of the pegmatite, as currently exposed, are 53 meters long by 1-15 meters wide with a vertical range of 50-60 meters.
		Near the center of the pegmatite, at the upper contact of the amazonite-topaz zone with the overlying perthite zone, a small area approximately 1 X 1.6 meters in size contained a concentration of coarsely crystalline ilmenite (to 10 cm), magnetite, zircon, rutile and several other minerals.
	www.findarticles.com /p/articles/mi_qa3672/is_199907/ai_n8875608/pg_2 (547 words)

	Aplite, pegmatite, and felsophyre dikes
		A zone of aplite and pegmatite dikes were emplaced along the contact between the metavolcanic and plutonic rocks in the Alabama Hills.
		The aplites and pegmatites are interrelated which is indicated by the fact that some aplites have segregations of coarse textured pegmatites.
		A rock that is physically separated from the pegmatite and aplite dikes by greater than a mile is the felsophyre dike in the north end portion of the hypabyssal rocks.
	www.angelfire.com /extreme4/lkrwork/x170.htm (396 words)

	Pegmatite Summary
		Pegmatite is a very coarse-grained igneous rock that has a grain size of 20 mm or more; such rocks are referred to as pegmatitic.
		Pegmatites are important because they often contain other rare earth minerals and gemstones, such as aquamarine, tourmaline, topaz, fluorite, and apatite, often along with tin and tungsten minerals, among others.
		Pegmatites are also a source for rare earth minerals such as columbite and tantalite.
	www.bookrags.com /Pegmatite (718 words)

	Minerals Of A Wausau Pegmatite Rocks & Minerals - Find Articles (Site not responding. Last check: )
		Pegmatites are common and tend to occur in vaguely defined groupings that are usually separated by relatively barren granite, although isolated pegmatites are sometimes encountered.
		His type-four pegmatites consist of bodies with late-stage, selectively etched quartz and resulting vuggy zones with subsequently crystallized accessory minerals; these pegmatites are perhaps the most prolific sources of well-crystallized microminerals.
		Along with these pocket fragments was a considerable quantity of pegmatite that appeared to have underlain the pocket zone and was impregnated with greenish clay.
	www.findarticles.com /p/articles/mi_m0GDX/is_4_74/ai_58915139 (895 words)

	Crystal Sizes and Pegmatite Dikes
		Most pegmatites are small, but dimensions can vary from a few meters to hundreds of meters in the longest dimension and from 1 cm to as much as 200 meters in width....
		Since igneous pegmatites characteristically solidify late in igneous activity, they tend to be associated with plutonic or hypabyssal intrusions from which the volatile fractions could not readily escape.
		In one pegmatite dike near Madawaska, north of Bancroft, which was mined for feldspar, a single crystal measuring 7 meters long and weighing 300 tons was extracted.
	www.csun.edu /~vcgeo005/gentry/crystal.htm (1285 words)

	Black Hills Pegmatites
		Rocks within the pegmatites are primarily plagioclase feldspars (oligoclase and albite), potash feldspars (perthite and microcline), and quartz.
		Pegmatites are generally grouped within three major mining districts, which are the Keystone, Custer, and Hill City districts in the southern Hills, and the Tintic district in the northern Hills.
		The Hugo is a complicated pegmatite, and the knowledge gained from the study of this pegmatite has clarified many problems concerning the internal structure and genesis of zoned pegmatites (Norton, 1962).
	www.dakotamatrix.com /Black_Hills_pegmatites.asp (6472 words)

	Pegmatite 101
		Pegmatites may be several meters long and less than 1 meter thick or as much as 3000 meters long to 700 meters wide.
		Pegmatites are widely distributed in the earth’s crust and are found on all continents (yes…even Antarctica.).
		Pegmatites of Precambrian age (2.8 to 1.0 billion years) are the most abundant and widespread.
	www.pegmatology.com /basic_info.htm (1042 words)

	QUANTITATIVE LITERACY PRESENTATION - THE NATURE OF GEOLOGY
		Dilation due to intrusion of the pegmatite displaced the aplite segments in a direction perpendicular to the length of the pegmatite.
		Due to inhomogeneities in the pegmatite melt or in the surrounding rocks, the intrusion of the pegmatite was accompanied by dilation oblique to the length of the pegmatite.
		The pegmatite served as a barrier to a subsequent intrusion of aplite.
	academic.brooklyn.cuny.edu /geology/leveson/core/graphics/quantlit/x_steps.html (688 words)

	The Pegmatite Zone
		Pegmatites are known to contain aquamarine, tourmaline, beryl, topaz, cassiterite, fluorite, apatite, tin and tungsten plus a host of other minerals.
		The major pegmatite districts of California are the Mesa Grande District, Pala District, Ramona District, Coahuilla District, Rincon District, Ramona District, and Jacumba District.
		Crystallization of large quartz crystals usually occurs at 900 degrees C whereas in granitic pegmatites the temperature of crystallization is dropped to 550 degrees C or so resulting in large megascopic crystals as typically seen at the classic mines like the Stewart Lithia Mine in Pala, CA and the Himalaya Mine in Mesa Grande, CA.
	www.gemandmineral.com /peg.html (834 words)

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