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New arsenate minerals from the Arsenatnaya Fumarole, Tolbachik Volcano, Kamchatka, Russia; XII, Zubkovaite, Ca (sub 3) Cu (sub 3) (AsO (sub 4) ) (sub 4)

Igor V. Pekov, Inna S. Lykova, Atali A. Agakhanov, Dmitry I. Belakovskiy, Marina F. Vigasina, Sergey N. Britvin, Anna G. Turchkova, Evgeny G. Sidorov and Katharina S. Scheidl
New arsenate minerals from the Arsenatnaya Fumarole, Tolbachik Volcano, Kamchatka, Russia; XII, Zubkovaite, Ca (sub 3) Cu (sub 3) (AsO (sub 4) ) (sub 4)
Mineralogical Magazine (December 2019) 83 (6): 879-886

Abstract

The new mineral zubkovaite, Ca (sub 3) Cu (sub 3) (AsO (sub 4) ) (sub 4) , was found in the Arsenatnaya fumarole at the Second scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption, Tolbachik volcano, Kamchatka, Russia. It is associated with anhydrite, svabite, hematite, johillerite, tilasite, fluorophlogopite, sanidine and aphthitalite. Zubkovaite occurs as coarse prismatic crystals up to 0.01 mm X 0.01 mm X 0.2 mm combined in radiating aggregates or crusts. The mineral is transparent, bright sky-blue, turquoise-coloured or light bluish-green, with vitreous lustre. It is brittle, with imperfect cleavage. The Mohs' hardness is ca 3. D (sub calc) is 4.161 g cm (super -3) . Zubkovaite is optically biaxial (-), alpha = 1.747(5), beta = 1.774(5), gamma = 1.792(5) and 2V (sub meas) = 75(10) degrees . Chemical composition (wt.%, electron microprobe) is: CaO 19.22, CuO 27.37, As (sub 2) O (sub 5) 52.54, SO (sub 3) 0.67, total 99.80. The empirical formula based on 16 O apfu is Ca (sub 2.96) Cu (sub 2.97) (As (sub 3.945) S (sub 0.07) ) (sub Sigma 4.015) O (sub 16) . Zubkovaite is monoclinic, C2, a = 16.836(3), b = 5.0405(8), c = 9.1173(17) Aa, beta = 117.388(13) degrees , V = 687.0(2) Aa (super 3) and Z = 2. The strongest reflections of the powder XRD pattern [d,Aa (I) (hkl)] are: 7.44 (100) (2 01), 3.727 (79) (400, 2 02, 3 11), 3.334 (92) (1 12), 2.914 (73) (311), 2.765 (50) (6 01, 6 02), 2.591 (96) (3 13) and 2.521 (53) (020). The crystal structure is unique for minerals. It was solved from single-crystal X-ray diffraction data to R = 7.19%. The structure contains trimers of Cu (super 2+) -centred polyhedra (consisting of one distorted square CuO (sub 4) in the core and two distorted square pyramids CuO (sub 5) ) and two crystallographically independent As (super 5+) O (sub 4) tetrahedra playing different roles: As(2)O (sub 4) tetrahedra link neighbouring trimers into ribbons whereas As(1)O (sub 4) tetrahedra link adjacent ribbons into heteropolyhedral layers; Ca cations are located in the interlayer space. The mineral is named in honour of the Russian crystallographer and crystal chemist Natalia Vital'evna Zubkova (born 1976).


ISSN: 0026-461X
EISSN: 1471-8022
Serial Title: Mineralogical Magazine
Serial Volume: 83
Serial Issue: 6
Title: New arsenate minerals from the Arsenatnaya Fumarole, Tolbachik Volcano, Kamchatka, Russia; XII, Zubkovaite, Ca (sub 3) Cu (sub 3) (AsO (sub 4) ) (sub 4)
Affiliation: Moscow State University, Faculty of Geology, Moscow, Russian Federation
Pages: 879-886
Published: 201912
Text Language: English
Publisher: Mineralogical Society, London, United Kingdom
References: 16
Accession Number: 2020-006916
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, Fersman Mineralogical Museum, RUS, Russian FederationSaint Petersburg State University, RUS, Russian FederationRussian Academy of Sciences, Institute of Volcanology and Seismology, RUS, Russian FederationUniversity of Vienna, AUT, Austria
Country of Publication: United Kingdom
Secondary Affiliation: GeoRef, Copyright 2020, American Geosciences Institute. Abstract, Copyright, Mineralogical Society of Great Britain and Ireland. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 202006
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