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New zinc and potassium chlorides from fumaroles of the Tolbachik Volcano, Kamchatka, Russia; mineral data and crystal chemistry; III, Cryobostryxite, KZnCl (sub 3) .2H (sub 2) O

Igor V. Pekov, Natalia V. Zubkova, Sergey N. Britvin, Vasiliy O. Yapaskurt, Nikita V. Chukanov, Inna S. Lykova, Evgeny G. Sidorov and Dmitry Yu. Pushcharovsky
New zinc and potassium chlorides from fumaroles of the Tolbachik Volcano, Kamchatka, Russia; mineral data and crystal chemistry; III, Cryobostryxite, KZnCl (sub 3) .2H (sub 2) O
European Journal of Mineralogy (September 2015) 27 (6): 805-812

Abstract

The new mineral cryobostryxite, KZnCl (sub 3) .2H (sub 2) O, is found in the Northern fumarole field, at the First scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption, Tolbachik volcano, Kamchatka, Russia. Cryobostryxite is a secondary mineral formed in the upper, moderately hot (30-80 degrees C) zone of active fumaroles, probably as a product of the interactions between high-temperature volcanic sublimates and meteoric water. It is associated with gypsum, ralstonite and opal; earlier, primary minerals of the assemblage are sellaite, fluorite, halite, anhydrite, cotunnite, sofiite, flinteite, chubarovite, anglesite, challacolloite, zincomenite, saltonseaite, hollandite, hematite, jakobssonite, leonardsenite and olsacherite. Cryobostryxite occurs as anthodites (up to 0.5X2 mm), their aggregates (up to 4X5 mm), granular crusts (up to 2X2 mm) and, rarely, coarse prismatic to acicular crystals (up to 0.2X1 mm). The mineral is transparent, colourless, with vitreous lustre. It is brittle, cleavage is not observed. The Mohs hardness is ca. 2. D (sub meas) =2.30(2), D (sub calc) =2.300 g cm (super -3) . Cryobostryxite is optically biaxial (+), alpha =1.522(2), beta =1.530(2), gamma =1.576(2) and 2V (sub meas) =30(15) degrees . The chemical composition (wt.%, electron-microprobe data, H (sub 2) O calculated for 2 molecules per formula unit, pfu) is: K 14.85, Tl 4.08, Zn 25.82, Cl 41.70, H (sub 2) O(calc.) 14.19, total 100.64. The empirical formula calculated on the basis of K+Tl+Zn+Cl=5 apfu is (K (sub 0.96) Tl (super +) (sub 0.05) ) (sub Sigma 1.01) Zn (sub 1.00) Cl (sub 2.99) .2H (sub 2) O. Cryobostryxite is monoclinic, P2 (sub 1) /c, a=6.2795(3), b=10.1397(3), c=12.0829(7) Aa, beta =107.732(5) degrees , V=732.79(6) Aa (super 3) and Z=4. The strongest reflections of the powder X-ray diffraction pattern [d, Aa (I,%) (hkl)] are: 7.62 (30) (011), 5.986 (43) (100), 5.766 (35) (002), 3.907 (33) (-121), 3.466 (20) (121), 3.062 (100) (-202, 023), 2.996 (24) (-211, 200) and 2.853 (27) (-114). The crystal structure, solved from single-crystal X-ray diffraction data (R=0.0654), contains isolated Zn-centred tetrahedra ZnCl (sub 3) (H (sub 2) O) connected via eight-coordinated K-centred polyhedra KCl (sub 7) (H (sub 2) O) to form a pseudo-framework. Both Zn- and K-centred polyhedra involve only O(1) atoms of the H (sub 2) O(1) molecules, whereas H (sub 2) O(2) molecules are located in holes of the K-Zn-Cl-H (sub 2) O(1) polyhedral pseudo-framework. The mineral name is based on two Greek words, kappa rho upsilon omicron zeta , cold or ice, and beta omicron sigma3Trho upsilon xi omicron struj, curl, reflecting the typical appearance: visually, anthodites of the mineral are very similar to ice curls. A novel chemical family of minerals including the potassium zinc chlorides flinteite K (sub 2) ZnCl (sub 4) , mellizinkalite K (sub 3) Zn (sub 2) Cl (sub 7) and cryobostryxite is discussed in the light of crystal-chemical data and formation conditions.


ISSN: 0935-1221
EISSN: 1617-4011
Serial Title: European Journal of Mineralogy
Serial Volume: 27
Serial Issue: 6
Title: New zinc and potassium chlorides from fumaroles of the Tolbachik Volcano, Kamchatka, Russia; mineral data and crystal chemistry; III, Cryobostryxite, KZnCl (sub 3) .2H (sub 2) O
Affiliation: Moscow State University, Faculty of Geology, Moscow, Russian Federation
Pages: 805-812
Published: 20150902
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Germany
References: 20
Accession Number: 2015-091714
Categories: Mineralogy of non-silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 6 tables
N55°40'59" - N55°40'59", E160°13'59" - E160°13'59"
Secondary Affiliation: Saint Petersburg State University, RUS, Russian FederationRussian Academy of Sciences, Institute of Problems of Chemical Physics, RUS, Russian FederationRussian Academy of Sciences, Institute of Volcanology and Seismology, 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: 201539
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