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Calciolangbeinite; K (sub 2) Ca (sub 2) (SO (sub 4) ) (sub 3) , a new mineral from the Tolbachik Volcano, Kamchatka, Russia

I. V. Pekov, M. E. Zelenski, N. V. Zubkova, V. O. Yapaskurt, N. V. Chukanov, D. I. Belakovskiy and D. Yu. Pushcharovsky
Calciolangbeinite; K (sub 2) Ca (sub 2) (SO (sub 4) ) (sub 3) , a new mineral from the Tolbachik Volcano, Kamchatka, Russia
Mineralogical Magazine (June 2012) 76 (3): 673-682

Abstract

The new mineral calciolangbeinite, ideally K (sub 2) Ca (sub 2) (SO (sub 4) ) (sub 3) , is the Ca-dominant analogue of langbeinite. It occurs in sublimates at the Yadovitaya fumarole on the Second scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure eruption, Tolbachik volcano, Kamchatka, Russia. The mineral is associated with langbeinite, piypite, hematite, rutile, pseudobrookite, orthoclase, lyonsite, lammerite, cyanochroite and chlorothionite. Calciolangbeinite occurs as tetrahedral to pseudo-octahedral crystals, which are bounded by {111} and {111i}, and as anhedral grains up to 1 mm in size, aggregated into clusters up to 2 mm across, and forming crusts covering areas of up to 1.5X1.5 cm on the surface of volcanic scoria. Late-stage calciolangbeinite occurs in complex epitaxial intergrowths with langbeinite. Calciolangbeinite is transparent and colourless with white streak and vitreous lustre. Its Mohs' hardness is 3-3 1/2. It is brittle, has a conchoidal fracture and no obvious cleavage. The measured and calculated densities are D (sub meas) = 2.68(2) and D (sub calc) = 2.74 g cm (super -3) , respectively. Calciolangbeinite is optically isotropic with n = 1.527(2). The chemical composition of the holotype specimen is Na (sub 2) O 0.38, K (sub 2) O 21.85, MgO 6.52, CaO 16.00, MnO 0.27, FeO 0.08, Al (sub 2) O (sub 3) 0.09, SO (sub 3) 55.14, total 100.63 wt.%. The empirical formula, calculated on the basis of twelve oxygen atoms per formula unit, is K (sub 2.01) (Ca (sub 1.24) Mg (sub 0.70) Na (sub 0.05) Mn (sub 0.02) Fe (sub 0.01) Al (sub 0.01) ) (sub Sigma 2 .03) S (sub 3.00) O (sub 12) . Calciolangbeinite is cubic, space group P2 (sub 1) 3, a = 10.1887(4) Aa, V = 1057.68(4) Aa (super 3) and Z = 4. The strongest reflections in the X-ray powder pattern [listed as (d,Aa(I)(hkl)] are 5.84(8)(111); 4.54(9)(120); 4.15(27)(211); 3.218(100)(310,130); 2.838(8)(230,320), 2.736(37)(231,321), 2.006(11)(431,341), 1.658(8)(611,532,352). The crystal structure was refined from single-crystal X-ray diffraction data to R = 0.0447. The structure is based on the langbeinite-type three-dimensional complex framework, which is made up of (Ca,Mg)O (sub 6) octahedra (Ca and Mg are disordered) and SO (sub 4) tetrahedra. Potassium atoms occupy two sites in voids in the framework; K(1) cations are located in ninefold polyhedra whereas K(2) cations are sited in significantly distorted octahedra. Calciolangbeinite and langbeinite are isostructural and form a solid-solution series.


ISSN: 0026-461X
EISSN: 1471-8022
Coden: MNLMBB
Serial Title: Mineralogical Magazine
Serial Volume: 76
Serial Issue: 3
Title: Calciolangbeinite; K (sub 2) Ca (sub 2) (SO (sub 4) ) (sub 3) , a new mineral from the Tolbachik Volcano, Kamchatka, Russia
Affiliation: Moscow State University, Moscow, Russian Federation
Pages: 673-682
Published: 201206
Text Language: English
Publisher: Mineralogical Society, London, United Kingdom
References: 19
Accession Number: 2012-092176
Categories: Mineralogy of non-silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 6 tables
N55°49'02" - N55°49'02", E160°22'02" - E160°22'02"
Secondary Affiliation: Russian Academy of Sciences, Institute of Experimental Mineralogy, RUS, Russian FederationRussian Academy of Sciences, Institute of Problems of Chemical Physics, RUS, Russian FederationRussian Academy of Sciences, Fersman Mineralogical Museum, RUS, Russian Federation
Country of Publication: United Kingdom
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, Copyright, Mineralogical Society of Great Britain and Ireland. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201248
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