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New arsenate minerals from the Arsenatnaya fumarole, Tolbachik Volcano, Kamchatka, Russia; VII, Pharmazincite, KZnAsO (sub 4)

Igor V. Pekov, Vasiliy O. Yapaskurt, Dmitry I. Belakovskiy, Marina F. Vigasina, Natalia V. Zubkova and Evgeny G. Sidorov
New arsenate minerals from the Arsenatnaya fumarole, Tolbachik Volcano, Kamchatka, Russia; VII, Pharmazincite, KZnAsO (sub 4)
Mineralogical Magazine (August 2017) 81 (4): 1001-1008

Abstract

The new mineral pharmazincite, KZnAsO (sub 4) , was found in sublimates of the Arsenatnaya fumarole at the Second scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption, Tolbachik volcano, Kamchatka, Russia. It is closely associated with shchurovskyite, dmisokolovite, bradaczekite, arsmirandite, tilasite, johillerite, tenorite, hematite, aphthitalite and As-bearing orthoclase. Pharmazincite occurs as prismatic to acicular crystals up to 1 mm long and up to 0.03 mm thick typically combined in near-parallel, radial or chaotic intergrowths, open-work aggregates or crusts up to 2 mm across. Pharmazincite is colourless to white, transparent, with a vitreous lustre. It is brittle, with a stepped fracture and a perfect cleavage parallel to [001]. D (sub calc) is 4.75 g cm (super -3) Pharmazincite is optically uniaxial (-), omega = 1.649(2), epsilon = 1.642(2). The Raman spectrum is reported. The chemical composition (wt.%, electron-microprobe data) is: K (sub 2) O 18.98, CaO 0.14, MgO 1.20, CuO 4.41, ZnO 27.58, Fe (sub 2) O (sub 3) 0.15, P (sub 2) O (sub 5) 0.50, As (sub 2) O (sub 5) 46.67, total 99.63. The empirical formula, calculated based on 4 O apfu, is: (K (sub 0.97) Ca (sub 0.01) ) (sub Sigma 0.98) (Zn (sub 0.82) Cu (sub 0.13) Mg (sub 0.07) Fe (super 3+) (sub 0.01) ) (sub Sigma 1.03) (As (sub 0.98) P (sub 0.02) ) (sub Sigma 1.00) O (sub 4) . The strongest reflections of the powder X-ray diffraction pattern [d,A(I)(hkl)] are: 6.36(28)(111), 4.64(45)(220), 4.35(48)(002), 3.260(36)(411), 3.179(100)(222), 2.770(26)(113), 2.676(77)(600), 2.278(15)(602) and 1.710(15)(713, 115). Pharmazincite is hexagonal, a = 18.501(4), c = 8.7114(9) A, V = 2582.4(8) A (super 3) and Z = 24 (single-crystal XRD data). Its space group is P6 (sub 3) , by analogy with synthetic KZnAsO (sub 4) that has a crystal structure based upon a tetrahedral tridymite-type {ZnAsO (sub 4) } (super -) framework. It is isostructural with megakalsilite KAlSiO (sub 4) . The new mineral is named for its chemical constituents.


ISSN: 0026-461X
EISSN: 1471-8022
Coden: MNLMBB
Serial Title: Mineralogical Magazine
Serial Volume: 81
Serial Issue: 4
Title: New arsenate minerals from the Arsenatnaya fumarole, Tolbachik Volcano, Kamchatka, Russia; VII, Pharmazincite, KZnAsO (sub 4)
Affiliation: Moscow State University, Faculty of Geology, Moscow, Russian Federation
Pages: 1001-1008
Published: 201708
Text Language: English
Publisher: Mineralogical Society, London, United Kingdom
References: 15
Accession Number: 2017-072974
Categories: Mineralogy of non-silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 1 table
N55°49'02" - N55°49'02", E160°22'02" - E160°22'02"
Secondary Affiliation: Russian Academy of Sciences, 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: 201738
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