Crystal chemistry of pyroaurite from the Kovdor Pluton, Kola Peninsula, Russia, and the Långban Fe–Mn deposit, Sweden

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Marco E. Ciriotti
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Crystal chemistry of pyroaurite from the Kovdor Pluton, Kola Peninsula, Russia, and the Långban Fe–Mn deposit, Sweden

Messaggio da Marco E. Ciriotti » gio 15 mar, 2018 10:32

Referenza:
▪ Zhitova, E.S., Ivanyuk, G.Yu., Krivovichev, S.V., Yakovenchuk, V.N., Pakhomovsky, Ya.A., Mikhailova, Yu.A. (2018): Crystal Chemistry of Pyroaurite from the Kovdor Pluton, Kola Peninsula, Russia, and the Långban Fe–Mn deposit, Värmland, Sweden. Geology of Ore Deposits, 59, 652-662.

Abstract:
Pyroaurite [Mg6Fe3+2(OH)16][(CO3)(H2O)] from the Kovdor Pluton on the Kola Peninsula, Russia, and the Långban deposit in Filipstad, Värmland, Sweden were studied with single crystal and powder X‑ray diffraction, an electron microprobe, and Raman spectroscopy. Both samples are rhombohedral, space group Rm, a = 3.126(3), c = 23.52(2) Å (Kovdor), and a = 3.1007(9), c = 23.34(1) (Långban). The powder XRD revealed only the 3R polytype. The ratio of di- and trivalent cations M2+ : M3+ was determined as ~3.1–3.2 (Kovdor) and ~3.0 (Långban). The Raman spectroscopy of the Kovdor sample verified hydroxyl groups and/or water molecules in the mineral (absorption bands in the region of 3600–3500 cm–1) and carbonate groups (absorption bands in the region of 1346–1058 cm–1). Based on the data obtained, the studied samples should be identified as pyroaurite-3R (hydrotalcite group).
Marco E. Ciriotti

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