Mineralogy and Crystallography

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spinel

A Dictionary of Earth Sciences | 1999 | | Copyright

spinel Important group of non-silicate mineral oxides, including the subgroups spinel series, magnetite series, and chromite series. Members of the spinel series have the general formula XAl₂O₄, where X = Mg in spinel, X = Fe²⁺ in hercynite, X = Zn in gahnite, and X = Mn in galaxite. Complete solid solution exists between all four end-members and also magnesiochromite (MgCr₂O₄); spinels with appreciable Fe²⁺ (Mg:Fe = 1:3) are called pleonaste and those with Fe²⁺ and Cr³⁺ are called mitchellite; sp. gr. 3.5–4.1; hardness 7.5–8.0; spinel is dark green and hercynite is dark bluish-green; all occur as small octohedra. Unlike chromite, which occurs in ultramafic (see ULTRABASIC) igneous intrusions, spinel may occur in metamorphic schists and gneisses with sillimanite, garnet, and cordierite. In contact metamorphosed impure limestones spinel occurs with chondrodite, olivine, and orthopyroxene, and in emery deposits it occurs with corundum. Spinel may develop in residual aluminous xenoliths enclosed in basic magmatic rocks. Spinel is found in alluvial deposits and gem quality spinel also occurs. Hercynite occurs in metamorphosed laterites; gahnite in granite pegmatites; and galaxite in manganese vein deposits.

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AILSA ALLABY and MICHAEL ALLABY. "spinel." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>.

AILSA ALLABY and MICHAEL ALLABY. "spinel." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O13-spinel.html

AILSA ALLABY and MICHAEL ALLABY. "spinel." A Dictionary of Earth Sciences. 1999. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O13-spinel.html

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spinel

The Columbia Encyclopedia, 6th ed. | 2011 | Copyright

spinel magnesium aluminum oxide, MgAl ₂ O ₄ , a mineral crystallizing in the isometric system, usually as octahedrons. It occurs as an accessory mineral in basic igneous rocks, in aluminum-rich metamorphic rocks, and in contact-metamorphosed limestones. Common spinel usually ranges in color from dark green to brown or black, but transparent red, blue, and green varieties are found and are used as gemstones; Myanmar and Sri Lanka are the principal producing countries. Much gem-quality spinel is now produced synthetically.

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"spinel." The Columbia Encyclopedia, 6th ed.. 2011. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1E1-spinel.html

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spinel

The Concise Oxford Dictionary of English Etymology | 1996 | | Copyright

spinel gem resembling the ruby. XVI. — F. spinelle — It. spinella, dim. of spina spine
.

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T. F. HOAD. "spinel." The Concise Oxford Dictionary of English Etymology. 1996. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>.

T. F. HOAD. "spinel." The Concise Oxford Dictionary of English Etymology. 1996. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O27-spinel.html

T. F. HOAD. "spinel." The Concise Oxford Dictionary of English Etymology. 1996. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O27-spinel.html

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spinel

Oxford Dictionary of Rhymes | 2007 | Copyright

spinel •Adele, Aix-la-Chapelle, aquarelle, artel, au naturel, bagatelle, béchamel, befell, bell, belle, boatel, Brunel, Cadell, carousel, cartel, cell, Chanel, chanterelle, clientele, Clonmel, compel, Cornell, crime passionnel, dell, demoiselle, dispel, dwell, el, ell, Estelle, excel, expel, farewell, fell, Fidel, fontanelle, foretell, Gabrielle, gazelle, gel, Giselle, hell, hotel, impel, knell, lapel, mademoiselle, maître d'hôtel, Manuel, marcel, matériel, mesdemoiselles, Michel, Michelle, Miguel, misspell, morel, moschatel, Moselle, motel, muscatel, nacelle, Nell, Nobel, Noel, organelle, outsell, Parnell, pell-mell, personnel, propel, quell, quenelle, rappel, Raquel, Ravel, rebel, repel, Rochelle, Sahel, sardelle, sell, shell, show-and-tell, smell, Snell, spell, spinel, swell, tell, undersell, vielle, villanelle, well, yell •Buñuel • Pachelbel • handbell •barbell • harebell • decibel • doorbell •cowbell • bluebell • Annabel •mirabelle • Christabel • Jezebel •Isabel, Isobel •nutshell • infidel • asphodel •zinfandel • Grenfell • Hillel • parallel •Cozumel • caramel • Fresnel •pimpernel • pipistrelle • Tricel •filoselle

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Free newspaper and magazine articles

	Spinel. (Jewel of the Month).(Brief Article) Magazine article from: Jewelers Circular Keystone; 3/1/2002
	VIETNAMESE SPINEL: Think Pink.(Gem Profile) Magazine article from: Modern Jeweler; 11/1/2007
	TANZANIAN SPINEL: Racing for the Red.(Gem Profile) Magazine article from: Modern Jeweler; 2/1/2008