minerals Article Dioskouriite, CaCu4Cl6(OH)4·4H2O: A New Mineral Description, Crystal Chemistry and Polytypism Igor V. Pekov 1,*, Natalia V. Zubkova 1, Andrey A. Zolotarev 2 , Vasiliy O. Yapaskurt 1, Sergey V. Krivovichev 2,3 , Dmitry I. Belakovskiy 4, Inna Lykova 5, Marina F. Vigasina 1 , Anatoly V. Kasatkin 4 , Evgeny G. Sidorov 6 and Dmitry Yu. Pushcharovsky 1 1 Faculty of Geology, Moscow State University, Vorobievy Gory, 119991 Moscow, Russia;
[email protected] (N.V.Z.);
[email protected] (V.O.Y.);
[email protected] (M.F.V.);
[email protected] (D.Yu.P.) 2 Department of Crystallography, Institute of Earth Sciences, St. Petersburg State University, 199034 St Petersburg, Russia;
[email protected] (A.A.Z.);
[email protected] (S.V.K.) 3 Kola Science Centre, Russian Academy of Sciences, 184209 Apatity, Russia 4 Fersman Mineralogical Museum of the Russian Academy of Sciences, 119071 Moscow, Russia;
[email protected] (D.I.B.);
[email protected] (A.V.K.) 5 Canadian Museum of Nature, P.O. Box 3443, Station D, Ottawa, ON K1P 6P4, Canada;
[email protected] 6 Institute of Volcanology and Seismology, Far Eastern Branch of Russian Academy of Sciences, 683006 Petropavlovsk-Kamchatsky, Russia;
[email protected] * Correspondence:
[email protected]; Tel.: +7-4959394676 Abstract: A new mineral, dioskouriite, CaCu4Cl6(OH)4·4H2O, represented by two polytypes, mon- oclinic (2M) and orthorhombic (2O), which occur together, was found in moderately hot zones of two active fumaroles, Glavnaya Tenoritovaya and Arsenatnaya, at the Second scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption, Tolbachik volcano, Kamchatka, Citation: Pekov, I.V.; Zubkova, N.V.; Zolotarev, A.A.; Yapaskurt, V.O.; Russia.