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Iyoite, MnCuCl(OH) 3 and misakiite, Cu 3 Mn(OH) 6 Cl 2 : new members of the atacamite family from Sadamisaki Peninsula, Ehime Prefecture, Japan

2017; Cambridge University Press; Volume: 81; Issue: 3 Linguagem: Inglês

10.1180/minmag.2016.080.104

1471-8022

Daisuke Nishio‐Hamane, Koichi Momma, M. Ohnishi, Norimasa Shimobayashi, Ritsuro Miyawaki, Norimitsu Tomita, Ryutaro Okuma, Anthony R. Kampf, Tetsuo Minakawa,

Advanced Condensed Matter Physics

Abstract Two new members of the atacamite family were discovered recently in the Sadamisaki Peninsula, Ehime Prefecture, Japan. Iyoite, MnCuCl(OH) 3 , is an Mn-Cu ordered analogue of botallackite, while misakiite, Cu 3 Mn(OH) 6 Cl 2 , is an Mn-rich analogueof kapellasite. Both minerals occur in manganese ore crevices in close association with one another. Iyoite forms radial and dendritic aggregates consisting of pale green, bladed crystals. Misakiite commonly exists in emerald green, tabular, hexagonal crystals. The densities of iyoite andmisakiite were calculated to be 3.22 and 3.42 g cm –3 based on their empirical formulae and powder X-ray diffraction data. Under the same axial setting of botallackite, iyoite is monoclinic, space group P 2 1 / m , a = 5.717(2), b = 6.586(2), c = 5.623(3) Å, β = 88.45(3)° and V = 211.63(15) Å 3 . Misakiite is trigonal, space group P 3 m 1, with a = 6.4156(4), c = 5.7026(5) Å and V = 203.27(3) Å 3 . The structures of both mineralsare classified as layer type and the two are closely related. These new minerals were formed by the reaction between seawater and naturally-occurring manganese ores including native copper. These minerals are challenging to produce synthetically. Misakiite was synthesized successfully usinga hydrothermal method, while iyoite could not be made.