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GEOREF RECORD

Khesinite, Ca (sub 4) Mg (sub 2) Fe (super 3+) (sub 10) O (sub 4) [(Fe (super 3+) (sub 10) Si (sub 2) )O (sub 36) ], a new rhonite-group (sapphirine supergroup) mineral from the Negev Desert, Israel; natural analogue of the SFCA phase

Irina O. Galuskina, Evgeny V. Galuskin, Anna S. Pakhomova, Remo Widmer, Thomas Armbruster, Biljana Krueger, Edward S. Grew, Yevgeny Vapnik, Piotr Dzierazanowski and Mikhail Murashko
Khesinite, Ca (sub 4) Mg (sub 2) Fe (super 3+) (sub 10) O (sub 4) [(Fe (super 3+) (sub 10) Si (sub 2) )O (sub 36) ], a new rhonite-group (sapphirine supergroup) mineral from the Negev Desert, Israel; natural analogue of the SFCA phase
European Journal of Mineralogy (March 2017) 29 (1): 101-116

Abstract

Khesinite, Ca (sub 4) Mg (sub 2) Fe (super 3+) (sub 10) O (sub 4) (Fe (super 3+) (sub 10) Si (sub 2) )O (sub 36) , is a new member of the rhonite group of the sapphirine supergroup. Khesinite was discovered in thin veins of paralavas within fine-grained gehlenite rocks (hornfels) of the Hatrurim Complex in the Negev Desert, Israel. Paralavas are composed of rankinite, pseudowollastonite (rarely wollastonite), flamite, kalsilite, cuspidine and members of the solid-solution series: schorlomite-andradite, gehlenite-ackermanite-"Fe (super 3+) -gehlenite", magnesioferrite-spinel and fluorapatite-fluorellestadite. Accessory and rare minerals are represented by baryte, walstromite, fresnoite, vorlanite, barioferrite, hematite, perovskite, gurimite, zadovite, aradite and hexacelsian. Electron-microprobe analysis of the holotype khesinite gives the following empirical formula for 40 oxygens and 28 cations: Ca (sub 4) (Fe (super 3+) (sub 8.528) Mg (sub 1.635) Ca (sub 0.898) Ti (super 4+) (sub 0.336) Ni (super 2+) (sub 0.217) Mn (super 2+) (sub 0.155) Cr (super 2+) (sub 0.132) Fe (super 2+) (sub 0.098) ) (sub Sigma 12) [(Fe (super 3+) (sub 6.827) Al (sub 2.506) Si (sub 2.667) ) (sub Sigma 12) O (sub 40) ]. Khesinite is black to dark brown. It has semi-metallic lustre and does not show fluorescence. Cleavage and parting are not observed, fracture is irregular. Khesinite has a Mohs' hardness of 6; microhardness VHN (sub 50) is 943 kg mm (super -2) The calculated density is 4.097 g cm (super -3) In reflected light khesinite is grey with weak internal brown reflections. Reflectance data for the COM (Commission of Ore Mineralogy, IMA) wavelengths vary from approximately 13.4% (470 nm) to approximately 11.8% (700 nm). The crystal structure of khesinite [P 1 a = 10.5363(1), b = 10.9242(2), c = 9.0612(1) A, alpha = 106.340(1) degrees , beta = 95.765(1) degrees , gamma = 124.373(1) degrees , V = 780.54(2) A (super 3) ] was refined from X-ray single-crystal data to R (sub 1) = 0.046. The khesinite structure is close to that of the synthetic compounds SFCA and SFCAM. Khesinite crystallized in paralava from melt, sometimes forming isolated crystals, but more commonly reaction rims on magnesioferrite in association with pseudowollastonite and flamite at temperature not lower than 1200 degrees C.


ISSN: 0935-1221
EISSN: 1617-4011
Serial Title: European Journal of Mineralogy
Serial Volume: 29
Serial Issue: 1
Title: Khesinite, Ca (sub 4) Mg (sub 2) Fe (super 3+) (sub 10) O (sub 4) [(Fe (super 3+) (sub 10) Si (sub 2) )O (sub 36) ], a new rhonite-group (sapphirine supergroup) mineral from the Negev Desert, Israel; natural analogue of the SFCA phase
Affiliation: University of Silesia, Department of Geochemistry, Mineralogy and Petrography, Sosnowiec, Poland
Pages: 101-116
Published: 201703
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Germany
References: 51
Accession Number: 2017-025976
Categories: Mineralogy of silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 9 tables
N31°08'60" - N31°08'60", E35°16'60" - E35°16'60"
Secondary Affiliation: University of Bayreuth, DEU, GermanyUniversity of Bern, CHE, SwitzerlandUniversity of Innsbruck, AUT, AustriaUniversity of Maine, USA, United StatesBen-Gurion University of the Negev, ISR, IsraelWarsaw University, POL, PolandSaint Petersburg State University, RUS, Russian Federation
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, copyright, Schweizerbart'sche Verlagsbuchhandlung. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201716
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