Muonionalustaite, Ni3(OH)4Cl2·4H2O, a new mineral formed by terrestrial weathering of the Muonionalusta iron (IVA) meteorite, Pajala, Norrbotten, Sweden. (2nd January 2021)

• Record Type: Journal Article
• Authors: Holtstam, Dan; Bindi, Luca; Karlsson, Andreas; Söderhielm, Johan; Zetterqvist, Anders
• Is Part Of: GFF. Volume 143:Number 1(2021)
• Page Start: 1
• Page End: 7
• Publication Date: 2021-01-02
• Subjects: Muonionalustaite -- new mineral -- nickel chloride -- meteorite weathering -- corrosion -- Muonionalusta -- Kitkiöjärvi; Geology -- Scandinavia -- Periodicals; Geology -- Periodicals; 554.8
• DOI: 10.1080/11035897.2020.1858342
• Languages: English
• ISSNs: 1103-5897

Abstract

ABSTRACT: Muonionalustaite, ideally Ni3 (OH)4 Cl2 · 4H2 O, is a new mineral species (IMA 2020–010), found as a terrestrial weathering product of the Muonionalusta iron meteorite, in a fragment excavated 1.5 km NE of Lake Kitkiöjärvi in northernmost Sweden. Muonionalustaite occurs in cavities of corrosion crust, associated with taenite, goethite, maghemite, amorphous Fe-Ni oxy-hydroxides and soil mineral particles. The mineral is green in colour and transparent. It occurs as lath-like crystals up to ca. 5 μm, elongated along [010] and flattened on {001}, forming aggregates and thin crusts. The calculated density and overall refractive index are 2.67(1) g·cm −3 and 1.68, respectively. An empirical formula from point analyses is (Ni2.88 Fe0.02 S0.02 Al0.01 Si0.01 )Σ2.94 (OH3.73 Cl2.27 )Σ6.00 · 4H2 O. The crystal structure was refined in the space group C 2 /m from powder X-ray diffraction data to R Bragg = 3.55%. The monoclinic unit-cell parameters are a = 15.018(3) Å, b = 3.1490(6) Å, c = 10.502(3) Å, β = 101.535(15)º and V = 486.62(19) Å 3 for Z = 2. Muonionalustaite is isostructural with the synthetic compounds Ni3 (OH)3.9 Cl2.1 · 4H2 O and Mg3 (OH)4 Cl2 · 4H2 O. The strongest X-ray diffraction lines are [ I (%), d (Å), hkl ]: 100, 10.30, 001; 67, 5.49, 201; 31, 3.868, 202; 30, 7.36, 200 and 25, 2.409, 6 ‾ 02. Raman spectra show prominent bands at 3624, 3612, 3571 and 3507 cm −1, related to O–H-stretching vibrations of OH − groups, and in the region 450–530 cm −1 representing metal–O(H) vibration modes.