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Topic: Pigeonite

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	Skaergaard intrusion photomicrographs
		Pigeonite exsolution lamellae occur also at other orientations but are not easily seen here.
		Cumulus phases are plagioclase, augite, olivine, pigeonite, and oxides.
		The orthopyroxene is in the center and lower parts of this image and is pinkish, the augite is mostly at the upper right and is greenish, and the olivine crystals are all rather rounded.
	www.union.edu /PUBLIC/GEODEPT/hollocher/skaergaard/geologic_features/micrographs.htm (2034 words)

	Ureilites
		Pigeonite shows well-defined twinning; graphite and carbonaceous-metal-silicate-masses tend to cross trend the lineation direction with some small masses poikilitically enclosed by large pigeonite.
		Fractures apparently served as channel ways for reducing (smelting) activity; grain edges have a saw tooth appearance of alternating, greater reduced rims together with deposits of carbonaceous-metal-silicate-masses that permeated fractures and less-reduced rims that are between fractures, similar to NWA 2624.
		Modal analyses of silicates (vol%): Olivine = 95, pigeonite = 3, orthopyroxene = 2.
	www4.nau.edu /meteorite/Meteorite/Ureilite.html (2199 words)

	Inosilcates
		Pigeonite is also a monoclinic pyroxene with a composition similar to the orthopyroxenes with more Ca substituting for Fe, and Mg.
		Thus, pigeonite is only found in volcanic and shallow intrusive igneous rocks, or as exsolution lamellae in a host augite or opx (more commonly in augite).
		Pigeonite is distinguished from augite by its lower 2V of 0 to 30
	www.tulane.edu /~sanelson/geol211/inosilicates.htm (1766 words)

	pigeonite.htm (Site not responding. Last check: 2007-10-11)
		Description: Pigeonite is a member of the pyroxene group found generally as small grains in gabbros, basalts, andesites, dacites and hornfels..
		It occurs with plagioclase and augite, and is difficult to identify.
		ASHLAND COUNTY: Pigeonite occurs as tiny grains in hornfels of the Ironwood iron formation in contact with the Mellen gabbro seen in outcrop in the SE NE sec.
	www.uwrf.edu /~william.s.cordua/pigeonite.htm (85 words)

	Mars Exploration: Newsroom
		A 70.2 gram meteorite completely coated with fusion-crust found in Morocco in December 2001 is almost certainly paired with basaltic shergottite NWA 480 (acquired in November 2000 by Bruno Fectay and Carine Bidaut).
		It consists mainly of large grains of compositionally zoned, low-Ca pyroxene (with orthopyroxene cores, augite mantles and pigeonite rims) and glassy, shocked plagioclase (maskelynite), with lesser amounts of two phosphate minerals (merrillite and chlorapatite), exsolved iron-titanium oxides, ilmenite, chromite, pyrrhotite, potassium-rich glass, silica and baddeleyite.
		A distinctive feature of both stones is the occurrence of complex intergrowths consisting of varying amounts of fayalite+hedenbergite+silica along the boundaries of pigeonite grains, which probably represent breakdown products of former pyroxferroite (an iron-rich pyroxene-like mineral first found in Apollo 11 lunar basalts).
	mars.jpl.nasa.gov /newsroom/pressreleases/20030212c.html (624 words)

	Pigeonite - Wikipedia, the free encyclopedia
		Polarized light microscope image of part of a grain of orthopyroxene containing exsolution lamellae of augite (long dimension 0.5 mm, Bushveld igneous complex).
		Pigeonite is a mineral in the clinopyroxene group.
		At lower temperatures, pigeonite is unstable relative to augite plus orthopyroxene.
	en.wikipedia.org /wiki/Pigeonite (212 words)

	KENNA PHOTO
		It is composed mainly of olivine and the calcium-poor pyroxene, pigeonite, in a fl carbon-rich matrix containing graphite, lonsdaleite, and diamond.
		The remainder of the monomict ureilites have an olivine-augite (augite-bearing) composition (only 8 examples are described), in which augite replaces the typical pigeonite.
		It is proposed that members of this subgroup formed early at the deepest layers, and are associated with the highest C content.
	www.meteoritestudies.com /protected_KENNA.HTM (1329 words)

	Union College Geology Department, Petrology page, lunar rocks and lunar thin sections, thin section images, feldspathic ...
		The basalts are referred to in Meyer (1987) as being "pigeonite basalts", unrelated to the mare basalts and presumably older.
		Closeup of one of the pigeonite basalt fragments, showing the fractured pyroxenes with considerable dark, fine-grained material that is not all Fe-Ti oxides.
		Interstitial material between pyroxenes and lath-shaped plagioclase crystals in one of the pigeonite basalt fragments.
	www.union.edu /PUBLIC/GEODEPT/COURSES/petrology/moon_rocks/72275.htm (378 words)

	Geokem
		Pigeonite may occur in the groundmass of tholeiitic basalts and in CFBs mantling the OPX phenocrysts.
		In CFB sills, the pigeonite is often inverted to an iron-rich Opx, with exsolved blebs of clinopyroxene scattered throughout.
		Neither pigeonite nor orthopyroxene occurs in alkaline ankaramites.
	www.geokem.com /minerals.html (2776 words)

	Monzogabbro 14161,7373
		The calculated REE concentrations of melt in equilibrium with pigeonite, after re-integration of pigeonite host and augite lamellae, is approximately 2 x high-K KREEP.
		The high bulk REE concentrations of the assemblage are the result of a high proportion of whitlockite, probably an excess, i.e., the assemblage is a whitlockite cumulate.
		Variations in silicate REE concentrations reflect the co-crystallization of whitlockite, which we interpret to have begun crystallizing prior to the onset of late-stage immiscibility of the felsic melt fraction.
	aaa.wustl.edu /Work/pub_files/monzogabbro_14161,7373.html (314 words)

	Martian Meteorites
		It is modally heterogeneous and is composed of ~40.7 % pigeonite, ~24.3 % augite, ~21.6 % olivine, and ~11.4 % maskelynite, with 2 % chromite, ilmenite, merrillite, and pyrrhotite.
		All maskelynite grains are rimmed by zones up to 40 μm in width consisting of a mixture of fine grained calcite, hydrous Al-rich silicate (possibly kaolinite), and very minor calcium chloride, which appear to be replacing the primary feldspar.
		% augite and pigeonite pyroxenes, and 38.3 vol.
	www4.nau.edu /meteorite/Meteorite/Martian.html (1676 words)

	Pigeonite
		L'aegyrine (trÃ¨s proche de la pigeonite reprÃ©sentÃ©e ici) a une forte birÃ©fringence (teintes de polarisation des...
		A comparative petrologic study of the Apollo 12 pigeonite basalt suite has been undertaken to answer the following questions: (1) What are the textural and petrologic variations within the pigeonite suite.^(2) Are these variations consistent with...
		The cooling history of an igneous or metamorphic rock is. of considerable importance to geologists.
	www.toprocks.net /MineralList/72/Pigeonite.asp (365 words)

	Petrography (Site not responding. Last check: 2007-10-11)
		The gray is coesite, and the mottled gray rim is polycrystalline quartz.
		This is an inverted pigeonite (pyroxene) from the Bushveld Complex in South Africa.
		On cooling the pigeonite (dark) host recrystallized to orthopyroxene epitaxially and then exsolved a second fine set of (1 0 0) lamellae which form the fine vertical streaks.
	ruby.colorado.edu /~smyth/Research/Images/Thinsections/Petro.html (449 words)

	NWA 2626
		The finer grained groundmass of the rock consists of compositionally-zoned clinopyroxene (pigeonite and some augite), maskelynitized plagioclase, smaller olivine grains, titanium-rich chromite, chromite, merrillite, ilmenite, ulvöspinel and pyrrhotite.
		Other distinctive features are irregular patches of late-crystallizing merrillite adjacent to groundmass pigeonite grains and within maskelynite grains, and moat-like cavities around maskelynite grains (which formerly may have contained soluble salts or soft alteration assemblages of Martian origin).
		NWA 2626 is further distinguished by the presence of cross-cutting veinlets and small pockets of dark glass with quenched crystallites, which are interpreted to have formed by shock-induced melting as this specimen was ejected from Mars.
	www2.jpl.nasa.gov /snc/nwa2626.html (791 words)

	NWA 2046
		This sample is very distinctive in containing large crystals of both olivine and orthopyroxene which exhibit a preferred alignment, probably as a result of crystal growth and transport by flow within a magma conduit beneath the surface of Mars.
		Image 5: False-color backscattered electron image of NWA 2046 showing prismatic orthopyroxene phenocryst and microphenocrysts (blue) mantled by pigeonite (green), with groundmass pigeonite (orange and yellow), olivine (white), maskelynite (fl), chromite and ilmenite (both white).
		The groundmass consists mainly of zoned pigeonite (Fs30Wo6.5 to Fs40Wo13) intergrown with maskelynite (zoned from cores of Ab25.5Or0.1 to rims of Ab36.5Or1.1) and small grains of relatively ferroan olivine (Fa47.6-58.1).
	www2.jpl.nasa.gov /snc/nwa2046.html (792 words)

	Amazon.com: "pigeonite lamellae": Key Phrase page (Site not responding. Last check: 2007-10-11)
		grew as a solid solution with composition between augite and pigeonite, and which subsequently has exsolved into coexisting augite and pigeonite lamellae.
		65.1.3a.4 Johannsenite 1301 augites may have exsolution lamellae of orthopyroxene parallel to {100} and pigeonite lamellae on irrational planes close to {100} or/and {001}.
		In Mg-rich augite, fine orthopyroxene and pigeonite lamellae have exsolved on (100) of the augite host, whereas more Fe-rich augites from the Banded Series contain both (001) and...
	www.amazon.com /phrase/pigeonite-lamellae (553 words)

	[No title]
		Mineralogy and classification (A. Burroni and L. Folco, MNA-SI): olivine and pigeonite ureilite with typical texture (average grain-size 1 mm).
		It consists mainly of ferroan pyroxenes (augite and pigeonite), and plagioclase glass with quenched plagioclase rims.
		The pigeonite composition Ca5Mg76Fe19 is uniform and the Fo values of olivine range from 78 to 79.
	www.meteorites4sale.net /MET_D.HTM (13322 words)

	Mars Meteorites / Shergottites (SNC) (Site not responding. Last check: 2007-10-11)
		Mineralogy: The members of this group consist primarily of the clinopyroxenes pigeonite and augite, minor plagioclase converted to maskelynite, and accessory phases such as fine-grained mesostasis, impact-melt, olivine, orthopyroxene, and various oxides, sulfides and phosphates.
		Several basaltic shergottites contain evidence of interaction with martian water, either in the form of hydrated silicates, or in the form of carbonate and sulfate salts.
		Mineralogy: Olivine-phyric shergottites are primarily composed of olivine phenocrysts set in a basaltic groundmass of pigeonite, plagioclase shock-converted to maskelynite, minor augite, and olivine.
	www.meteorites.tv /contents/en-us/d94.html (1221 words)

	eucrites - Eukrite, some originating from Vesta
		The texture of unbrecciated cumulate eucrites is equigranular with spyroxene and plagioclase grains 0.5-3 mm diameter (Hess and Henderson 1949, Lovering 1975, Mittlefehldt and Lindstrom.)
		The original igneous pyroxene of cumulate eucrites was pigeonite, which has subsequently undergone subsolidus exsolution of augite and, in some cases, inversion to orthopyroxene, with additional augite exsolution.
		(1976) have shown that the original pyroxene in Binda was a low-Ca pigeonite that exsolved augite and inverted to hypersthene.
	www.mars.li /eucrites.htm (1882 words)

	Gemstone, Gemstone Beads, Silver Jewellery, Gemstones Exporter (Site not responding. Last check: 2007-10-11)
		It forms complete solid solution series with hedenbergite (FeCaSi2O6) and augite, and partial solid solutions with orthopyroxene and pigeonite.
		At relatively high temperatures, there is a miscibility gap between diopside and pigeonite, and at lower temperatures, between diopside and orthopyroxene.
		At 5.5-6.5 on the Mohs scale, chrome diopside is relatively soft to scratch.
	www.nobelarts.net /chromediopside.htm (211 words)

	Basalt - Wikipedia, the free encyclopedia
		In tholeiitic basalt, pyroxene (augite and orthopyroxene or pigeonite) and calcium-rich plagioclase are common phenocryst minerals.
		Olivine may also be a phenocryst, and when present, may have rims of pigeonite.
		Olivine tholeiite has augite and orthopyroxene or pigeonite with abundant olivine, but olivine may have rims of pyroxene and is unlikely to be present in the groundmass.
	en.wikipedia.org /wiki/Basalt (1965 words)

	Northwest Africa 773 - Lunar Meteorite (Site not responding. Last check: 2007-10-11)
		Larger pigeonite grains commonly enclose equant olivine grains, which contain abundant melt inclusions (0.025–0.125 mm).
		Plagioclase is partially converted to maskelynite, and pyroxenes and olivine exhibit shock lamellae and undulatory extinction.
		Because augite and pigeonite, both clinopyroxenes, dominate over orthopyroxene, which is at most "minor" (Korotev et al., 2002), the cumulate is a gabbro, not a norite.
	epsc.wustl.edu /admin/resources/meteorites/nwa773.html (2129 words)

	Michael I. Casper's Meteorites Inc. Meteorites for Sale
		Ureilites are calcium-poor achondrites, consisting mainly of olivine, pigeonite (their dominant form of pyroxene) and carbon (2.2%).
		The carbon is in the form of either graphite, diamond, or lonsdaleite (a rare pure carbon mineral like diamond, but with a different crystal structure).
		Shergottites are pigeonite and augite-dominated basalts, samples of lavas that once flowed on their parent world.
	www.caspermeteorites.com /achondrites.html (944 words)

	SRI's (Site not responding. Last check: 2007-10-11)
		Los Angeles 001 is unusually coarse-grained indicating that it cooled from igneous temperatures (1200 C to 900 C) at a slower rate than other shergottites.
		This slower cooling resulted in a crystallization of the pyroxenes augite and pigeonite in lamellae easily visible to the unaided eye.
		In comparison, the augite in Zagami is almost an order of magnitude smaller than that observed in LA001.
	www.meteorlab.com /METEORLAB2001dev/labphoto/LA001.htm (296 words)

	[No title]
		Examples of two minerals, enstatite and pigeonite, that have gone through this process are shown in Figures 1 and 2 below:
		The SNR of the spectra is shown to the right of each.
		The broad feature near 2 um (e.g., enstatite, pigeonite) is detectable even in SNR=20 data for the pure mineral phases; however, substantial errors in derived spectral parameters arise if SNR < 50, and detailed mineralogic characterization would be difficult for SNR < 100 in many cases.
	marswatch.tn.cornell.edu /nis_05.html (737 words)

	Learn About Clinopyroxenes Page. Quartz 'N' All - High Quality Crystals, Minerals and Fossils (Site not responding. Last check: 2007-10-11)
		Below you will find the geological properties and some further information regarding Clinopyroxenes.These include Diopside, Augite, pigeonite, hedenbergite, titanaugite, omphacite spodumene and jadeite.
		Augite and pigeonite are calcium-poor varieties found in basalts, dolerites and andesites.
		Titanaugite, found in alkali-gabbos and alkali olivine basalts, has a high titanium content and is violet and purple-brown.
	www.quartznall.co.uk /learnclinopyroxene.htm (253 words)

	Pyroxene - Wikipedia, the free encyclopedia
		Increasing the calcium content prevents the formation of the orthorhombic phases and pigeonite ([Mg,Fe,Ca][Mg,Fe]Si) only crystallises in the monoclinic system.
		There is not complete solid solution in calcum content and Mg-Fe-Ca pyroxenes with calcium contents between about 15 and 25 mol.% are not stable with respect to a pair of exolved crystals.
		This leads to a miscibility gap between pigeonite and augite compositions.
	en.wikipedia.org /wiki/Pyroxene (910 words)

	Amazon.com: "augite host": Key Phrase page (Site not responding. Last check: 2007-10-11)
		Hence the pigeonite and augite crystallographic axes remain approximately parallel.
		The pigeonite grows as lamellae whose orientation within the augite host is determined by the minimum interfacial strain.
		In Mg-rich augite, fine orthopyroxene and pigeonite lamellae have exsolved on (100) of the augite host, whereas more Fe-rich augites from the Banded Series contain both (001) and (100) lamellae of low-Ca pyroxene.
	www.amazon.com /phrase/augite-host (337 words)

	DAG868 PHOTO
		Like most ureilites, DaG 868 is composed of grains of olivine (82 vol%) and pigeonite (11 vol%) along with carbonaceous material forming rims and veins.
		The small amount of metal present has been extremely weathered.
		These diamonds have a solar signature inferred by their C and N isotope compositions.
	www.meteoritestudies.com /protected_DAG868.HTM (349 words)

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