Iyoite, MnCuCl(OH)₃ and misakiite, Cu₃Mn(OH)₆Cl₂: new members of the atacamite family from Sadamisaki Peninsula, Ehime Prefecture, Japan

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, Cu3Mn(OH)6Cl2, 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 P21/m, a = 5.717(2), b = 6.586(2), c= 5.623(3) Å, β = 88.45(3)° and V = 211.63(15) Å3. Misakiite is trigonal, space group P3m1, with a = 6.4156(4), c = 5.7026(5) Å and V = 203.27(3) Å3. 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.

Quantum magnetism in minerals

“…It is described by the space group P 3m1 and is commonly referred to 1 as α-ZnCu 3 (OH) 6 Cl 2 . Its isostructural Mgand Mn-rich analogues haydeeite, α-MgCu 3 (OH) 6 Cl 2 [384], and misakiite, α-MnCu 3 (OH) 6 Cl 2 [385], are also known. In the first comparative study of kapellasite and haydeeite, Janson et al [261] employed electronic-structure and exact-diagonalization calculations to argue that further-neighbour exchange interactions across the kagome hexagons, shown in Fig.…”

“…65. Then, a newly discovered mineral iyoite, MnCuCl(OH) 3 [385], is a Mn-Cu ordered analogue of botallackite. Its structure is based on brucite-like sheets orthogonal to the a axis, built from distorted edge-sharing Mn(OH) 5 Cl and Cu(OH) 4 Cl octahedral chains that alternate along the c direction.…”

Synthesis and structure of calumetite-like SrCu4(OH)8Cl2⋅3.5H2O

“…a = 6.2733(4) Å and c = 5.7472(5) Å, haydeeite; Malcherek and Schlüter, 2007); Mn, a = 6.42533(17) Å and c = 5.71048(11) Å (cf. a = 6.4168(4) Å and c = 5.7099(4) Å, misakiite; Nishio-Hamane et al , 2017), centennialite, calumetite (and both together), Crichton and Müller (2017); clinoatacamite-like: Cd, with a = 6.3889(10) Å, b = 7.05329(11) Å, c = 9.3378(11) Å and β = 99.034(15)° (e.g. McQueen et al , 2011); Ni, with a = 6.1746(6) Å, b = 6.8821(5) Å, c = 9.0308(7) Å and β = 99.46(8)° and rhombohedral forms: Co, with a = 6.8476(4) Å and c = 14.1382(22) Å (cf.…”