Reference:
▪ Kampf, A.R., Mills, S.J., Nash, Barbara P., Dini, M., Molina Donoso, A.A. (2017): Currierite, Na4Ca3MgAl4(AsO3OH)12·9H2O, a new acid arsenate with ferrinatrite-like heteropolyhedral chains from the Torrecillas mine, Iquique Province, Chile. Mineralogical Magazine, 81, 1141-1149.
Abstract:
The new mineral currierite (IMA2016-030), Na4Ca3MgAl4(AsO3OH)12·9H2O, was found at the Torrecillas mine, Iquique Province, Chile, where it occurs as a secondary alteration phase in association with anhydrite, canutite, chudobaite, halite, lavendulan, magnesiokoritnigite, quartz, scorodite and torrecillasite. Currierite occurs as hexagonal prisms, needles and hair-like fibres up to about 200 μm long, in sprays. The crystal forms are {100} and {001}. Crystals are transparent, with vitreous to silky lustre and white streak. The Mohs hardness is ca. 2, tenacity is brittle, but elastic in very thin fibres, and the fracture is This irregular. Crystals 26 exhibit at least one good cleavage parallel [001]. The measured density is 3.08(2) g·cm–3 and the calculated density is 3.005 g·cm–3. Optically, currierite is uniaxial (–) with ω = 1.614(1) and ε = 1.613(1) (measured in white light). The mineral is slowly soluble in dilute HCl at room temperature. The empirical formula, determined from electron-microprobe analyses, is (Na3.95Al2.96Ca2.74Mg1.28Fe3+ 0.63Cu0.13K0.08Co0.03)Σ11.80(As5+ 11.68Sb5+ 0.32)Σ12 (O56.96Cl0.04)Σ57H30.81. Currierite is hexagonal, P622, with a = 12.2057(9), c = 9.2052(7) Å, V = 1187.7(2) Å3 and Z = 1. The eight strongest X-ray powder diffraction lines are [dobs Å(I)(hkl)]: 10.63(100)(100), 6.12(20)(110), 5.30(15)(200), 4.61(24)(002), 4.002(35)(210), 3.474(29)(202), 3.021(96)(212) and 1.5227(29)(440,334,612). The structure of currierite (R1 = 2.27% for 658 Fo > 4σF reflections) is based upon a heteropolyhedral chain along c in which AlO6 octahedra are triple-linked by sharing corners with AsO3OH tetrahedra. Chains are linked to one another by bonds to 8(4+4)-coordinated Na and 8-coordinated Ca forming a three-dimensional framework with large cavities that contain rotationally disordered Mg(H2O) octahedra. The chain in the structure of currierite is identical to that in kaatialaite and a geometrical isomer of that in ferrinatrite. The mineral is named in honour of Mr. Rock Henry Currier (1940-2015), American mineral dealer, collector, author and lecturer.
▪ Kampf, A.R., Mills, S.J., Nash, Barbara P., Dini, M., Molina Donoso, A.A. (2017): Currierite, Na4Ca3MgAl4(AsO3OH)12·9H2O, a new acid arsenate with ferrinatrite-like heteropolyhedral chains from the Torrecillas mine, Iquique Province, Chile. Mineralogical Magazine, 81, 1141-1149.
Abstract:
The new mineral currierite (IMA2016-030), Na4Ca3MgAl4(AsO3OH)12·9H2O, was found at the Torrecillas mine, Iquique Province, Chile, where it occurs as a secondary alteration phase in association with anhydrite, canutite, chudobaite, halite, lavendulan, magnesiokoritnigite, quartz, scorodite and torrecillasite. Currierite occurs as hexagonal prisms, needles and hair-like fibres up to about 200 μm long, in sprays. The crystal forms are {100} and {001}. Crystals are transparent, with vitreous to silky lustre and white streak. The Mohs hardness is ca. 2, tenacity is brittle, but elastic in very thin fibres, and the fracture is This irregular. Crystals 26 exhibit at least one good cleavage parallel [001]. The measured density is 3.08(2) g·cm–3 and the calculated density is 3.005 g·cm–3. Optically, currierite is uniaxial (–) with ω = 1.614(1) and ε = 1.613(1) (measured in white light). The mineral is slowly soluble in dilute HCl at room temperature. The empirical formula, determined from electron-microprobe analyses, is (Na3.95Al2.96Ca2.74Mg1.28Fe3+ 0.63Cu0.13K0.08Co0.03)Σ11.80(As5+ 11.68Sb5+ 0.32)Σ12 (O56.96Cl0.04)Σ57H30.81. Currierite is hexagonal, P622, with a = 12.2057(9), c = 9.2052(7) Å, V = 1187.7(2) Å3 and Z = 1. The eight strongest X-ray powder diffraction lines are [dobs Å(I)(hkl)]: 10.63(100)(100), 6.12(20)(110), 5.30(15)(200), 4.61(24)(002), 4.002(35)(210), 3.474(29)(202), 3.021(96)(212) and 1.5227(29)(440,334,612). The structure of currierite (R1 = 2.27% for 658 Fo > 4σF reflections) is based upon a heteropolyhedral chain along c in which AlO6 octahedra are triple-linked by sharing corners with AsO3OH tetrahedra. Chains are linked to one another by bonds to 8(4+4)-coordinated Na and 8-coordinated Ca forming a three-dimensional framework with large cavities that contain rotationally disordered Mg(H2O) octahedra. The chain in the structure of currierite is identical to that in kaatialaite and a geometrical isomer of that in ferrinatrite. The mineral is named in honour of Mr. Rock Henry Currier (1940-2015), American mineral dealer, collector, author and lecturer.