The new mineral alexkhomyakovite K6(Ca2Na)(CO3)5Cl∙6H2O (IMA2015-013) occurs in a peralkaline pegmatite at Mt. Koashva, Khibiny alkaline complex, Kola peninsula, Russia. It is a hydrothermal mineral associated with villiaumite, natrite, potassic feldspar, pectolite, sodalite, biotite, lamprophyllite, titanite, fluorapatite, wadeite, burbankite, rasvumite, djerfisherite, molybdenite and an incompletely characterized Na–Ca silicate. Alexkhomyakovite occurs as equant grains up to 0.2 mm, veinlets up to 3 cm long and up to 1 mm thick and fine-grained aggregates replacing delhayelite. Alexkhomyakovite is transparent to translucent, colourless, white or grey, with vitreous to greasy lustre. It is brittle, the Mohs hardness is ca. 3. No cleavage was observed, the fracture is uneven. Dmeas = 2.25(1), Dcalc = 2.196 g cm−3. Alexkhomyakovite is optically uniaxial (–), ω = 1.543(2), ε = 1.476(2). The infrared spectrum is reported. The chemical composition [wt%, electron microprobe data, CO2 and H2O contents calculated for 5 (CO3) and 6 (H2O) per formula unit (pfu), respectively] is: Na2O 4.09, K2O 35.72, CaO 14.92, MnO 0.01, FeO 0.02, SO3 0.11, Cl 4.32, CO2 28.28, H2O 13.90, –O=Cl –0.98, total 100.39. The empirical formula calculated on the basis of 9 metal cations pfu is K5.90Ca2.07Na1.03(CO3)5(SO4)0.01O0.05Cl0.95∙6H2O. The numbers of CO3 groups and H2O molecules are based on structure data. Alexkhomyakovite is hexagonal, P63/mcm, a = 9.2691(2), c = 15.8419(4) Å, V = 1178.72(5) Å3 and Z = 2. The strongest reflections of the powder X-ray diffraction pattern [d Å(I)(hkl)] are: 7.96(27)(002), 3.486(35)(113), 3.011(100)(114), 2.977(32)(211), 2.676(36)(300), 2.626(42)(213, 115), 2.206(26)(311) and 1.982(17)(008). The crystal structure (solved from single-crystal X-ray diffraction data, R = 0.0578) is unique. It is based on (001) heteropolyhedral layers of pentagonal bipyramids (Ca,Na)O5(H2O)2 interconnected via carbonate groups of two types, edge-sharing ones and vertex-sharing ones. Ca and Na are disordered. Ten-fold coordinated K cations centre KO6Cl(H2O)3 polyhedra on either side of the heteropolyhedral layer. A third type of carbonate group and Cl occupy the interlayer. The mineral is named in honour of the outstanding Russian mineralogist Alexander Petrovich Khomyakov (1933–2012).
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Research Article|
January 01, 2019
Alexkhomyakovite, K6(Ca2Na)(CO3)5Cl∙6H2O, a new mineral from the Khibiny alkaline complex, Kola peninsula, Russia
Igor V. Pekov;
1
Faculty of Geology, Moscow State University, Vorobievy Gory
, 119991Moscow, Russia
2
Vernadsky Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences
, Kosygina str. 19, 119991Moscow, Russia
Corresponding author, email: [email protected]
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Natalia V. Zubkova;
Natalia V. Zubkova
1
Faculty of Geology, Moscow State University, Vorobievy Gory
, 119991Moscow, Russia
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Vasiliy O. Yapaskurt;
Vasiliy O. Yapaskurt
1
Faculty of Geology, Moscow State University, Vorobievy Gory
, 119991Moscow, Russia
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Inna S. Lykova;
Inna S. Lykova
1
Faculty of Geology, Moscow State University, Vorobievy Gory
, 119991Moscow, Russia
3
Fersman Mineralogical Museum of Russian Academy of Sciences
, Leninsky Prospekt 18-2, 119071Moscow, Russia
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Nikita V. Chukanov;
Nikita V. Chukanov
4
Institute of Problems of Chemical Physics, Russian Academy of Sciences
, 142432Chernogolovka, Moscow region, Russia
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Dmitry I. Belakovskiy;
Dmitry I. Belakovskiy
3
Fersman Mineralogical Museum of Russian Academy of Sciences
, Leninsky Prospekt 18-2, 119071Moscow, Russia
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Sergey N. Britvin;
Sergey N. Britvin
5
Department of Crystallography, St Petersburg State University
, Universitetskaya Nab. 7/9, 199034St Petersburg, Russia
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Anna G. Turchkova;
Anna G. Turchkova
1
Faculty of Geology, Moscow State University, Vorobievy Gory
, 119991Moscow, Russia
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Dmitry Y. Pushcharovsky
Dmitry Y. Pushcharovsky
1
Faculty of Geology, Moscow State University, Vorobievy Gory
, 119991Moscow, Russia
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1
Faculty of Geology, Moscow State University, Vorobievy Gory
, 119991Moscow, Russia
2
Vernadsky Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences
, Kosygina str. 19, 119991Moscow, Russia
Natalia V. Zubkova
1
Faculty of Geology, Moscow State University, Vorobievy Gory
, 119991Moscow, Russia
Vasiliy O. Yapaskurt
1
Faculty of Geology, Moscow State University, Vorobievy Gory
, 119991Moscow, Russia
Inna S. Lykova
1
Faculty of Geology, Moscow State University, Vorobievy Gory
, 119991Moscow, Russia
3
Fersman Mineralogical Museum of Russian Academy of Sciences
, Leninsky Prospekt 18-2, 119071Moscow, Russia
Nikita V. Chukanov
4
Institute of Problems of Chemical Physics, Russian Academy of Sciences
, 142432Chernogolovka, Moscow region, Russia
Dmitry I. Belakovskiy
3
Fersman Mineralogical Museum of Russian Academy of Sciences
, Leninsky Prospekt 18-2, 119071Moscow, Russia
Sergey N. Britvin
5
Department of Crystallography, St Petersburg State University
, Universitetskaya Nab. 7/9, 199034St Petersburg, Russia
Anna G. Turchkova
1
Faculty of Geology, Moscow State University, Vorobievy Gory
, 119991Moscow, Russia
Dmitry Y. Pushcharovsky
1
Faculty of Geology, Moscow State University, Vorobievy Gory
, 119991Moscow, Russia
Corresponding author, email: [email protected]
Publisher: Deutsche Mineralogische Gesellschaft, Sociedad Española de Mineralogia, Societá Italiana di Mineralogia e Petrologia, Société Francaise de Minéralogie
Received:
30 Apr 2018
Revision Received:
01 Jun 2018
Accepted:
02 Jun 2018
First Online:
07 Sep 2018
Online ISSN: 1617-4011
Print ISSN: 0935-1221
© 2018 E. Schweizerbart’sche Verlagsbuchhandlung, 70176 Stuttgart, Germany
European Journal of Mineralogy (2019) 31 (1): 135–143.
Article history
Received:
30 Apr 2018
Revision Received:
01 Jun 2018
Accepted:
02 Jun 2018
First Online:
07 Sep 2018
Citation
Igor V. Pekov, Natalia V. Zubkova, Vasiliy O. Yapaskurt, Inna S. Lykova, Nikita V. Chukanov, Dmitry I. Belakovskiy, Sergey N. Britvin, Anna G. Turchkova, Dmitry Y. Pushcharovsky; Alexkhomyakovite, K6(Ca2Na)(CO3)5Cl∙6H2O, a new mineral from the Khibiny alkaline complex, Kola peninsula, Russia. European Journal of Mineralogy 2019;; 31 (1): 135–143. doi: https://doi.org/10.1127/ejm/2018/0030-2798
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Index Terms/Descriptors
- alkali metals
- alkaline earth metals
- calcium
- carbonates
- chemical composition
- Commonwealth of Independent States
- coordination
- electron probe data
- Europe
- formula
- granites
- hydrothermal alteration
- igneous rocks
- infrared spectra
- Khibiny Mountains
- Kola Peninsula
- metals
- metasomatism
- mineral interlayer
- Murmansk Russian Federation
- new minerals
- optical properties
- order-disorder
- pegmatite
- peralkalic composition
- physical properties
- plutonic rocks
- polyhedra
- potassium
- Russian Federation
- sodium
- spectra
- X-ray diffraction data
- Mount Koashva
- alexkhomyakovite
Latitude & Longitude
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