01 – A SECOND OCCURRENCE OF MUONIONALUSTAITE, Ni3Cl2(OH)4·4H2O, THE Ni ANALOGUE OF A SOREL CEMENT PHASE
Ano 09 (2022) – Special Issue on Herbert Artigos
10.31419/ISSN.2594-942X.v92022iSpeciala1TW
Thomas Witzke1) and Jürgen Göske2)
1) Malvern Panalytical, X-ray Application Laboratory, Lelyweg 1, 7602 EA Almelo, The Netherlands
2) Zentrum für Werkstoffanalytik, Hardtstraße 39b, 91207 Lauf an der Pegnitz, Germany
dedicated to Herbert Pöllmann, in memorian
Note: originally a small paper together with Herbert Pöllmann about the nickel chloride mineral, zaratite and the relation to Sorel cement phases was planned.
ABSTRACT
This paper describes a new occurrence of muonionalustaite from small light green spheres on the „zaratite“ sample from the Lord Brassey Mine. The amount of material is very small and in total less than a cubic millimetre. Muonionalustaite is the natural analogue of synthetic Ni3Cl2(OH)4·4H2O and the Ni-analogue of synthetic Mg3Cl2(OH)4·4H2O.
Keywords: Lord Brassey Mine, Heazlewood district, Tasmania, Australia, gaspeite, nullaginite, otwayite, zaratite.
INTRODUCTION
During an investigation of samples labeled as “zaratite“ from the Lord Brassey mine, Heazlewood district, Tasmania, Australia, a few small spheres with an intense light green colour were observed (Figure 1) on a single specimen next to darker green, glassy material. While the latter fit to the description of zaratite, the light green spheres resemble more other nickel minerals like nullaginite.
The Lord Brassey Mine, an abandoned nickel mine, is the type locality for the minerals heazlewoodite, Ni3S2, and hellyerite, NiCO3·6H2O. Several other rare nickel minerals were found there, like gaspéite, nullaginite, otwayite and zaratite. Zaratite is an ill-defined, amorphous nickel carbonate, but also badly crystalline material, showing a few broad diffraction lines is attributed to this mineral. The formula is usually given as Ni3(CO3)(OH)4·4H2O and was already established (in a different notation) by Smith & Brush (1853). According to an investigation of the type specimen of zaratite from Cape Ortegal, Spain, and zaratite samples from Texas, Lancaster Co., Pennsylvania, USA, and Heazlewood, Tasmania, Australia (Garcia-Guinea et al., 2013), the mineral is X-ray amorphous (weak diffraction lines are from impurities) and shows a large compositional range with a variable carbonate-hydroxide ratio and water content. From the observed compositions, a general formula for zaratite Ni3(CO3)1+x(OH)4-2x·nH2O with x = 0.3 – 2 and n < 3.5 can be given. Minor and trace amounts of chloride and sulfate are regarded as non-essential. The formula usually attributed to zaratite is outside this range. Generally, samples labeled as zaratite may represent more than one mineral species.
ANALYSIS OF THE NICKEL CHLORIDE PHASE
The small light green spheres on the „zaratite“ sample from the Lord Brassey Mine were prepared for a first X-ray diffraction analysis on a zero background silicon disc and was measured on an Empyrean diffractometer (Malvern Panalytical) with CuKα radiation and PIXcel detector. It was found to be a well crystalline material, completely different from zaratite. The powder diffraction data did not fit to any known mineral at this time, but match well to synthetic Ni3Cl2(OH)4·4H2O, described by Bette et al. (2014). A Rietveld refinement (program HighScore Plus) yielded a monoclinic cell with a = 14.998, b = 3.150, c = 10.485 Å, β = 101.62°, V = 485.23 Å3 from the powder data. A SEM-EDS analysis confirmed the identification. A composition of Ni3Cl1.92(OH)4.08·nH2O (calculated on Ni = 3, OH from stoichiometry, water content not determined) was found for the material.
The amount of material is very small and in total less than a cubic millimetre. The small spheres have a dimeter of less than 0.5 millimetre. The spheres are composed of tiny, prismatic to lath-like crystals of 0.1 – 1 µm thickness, 1 – 5 µm width and several µm length (Figure 2). The streak is light green like the colour, Mohs hardness is around 1 – 2. The mineral has a glassy to silky lustre. The mineral is accompanied by antigorite, metallic grey heazlewoodite, and green glassy, amorphous zaratite. Evaluation of the powder diffraction data showed also the presence of small amounts of Ni3Cl2(OH)4·2H2O. This phase is also known synthetically (Bette et al., 2016). The intimate intergrowth and the small amount of the dihydrate phase make it impossible to characterize it as a new mineral.
MUONIONALUSTAITE
During further investigation for the full description of Ni3Cl2(OH)4·4H2O from Tasmania (Figures 1 and 2) as a new mineral it was known that an identical mineral was submitted under the name muonionalustaite from another group for acceptance to the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association. Further work on the material from Tasmania was therefore stopped. Muonionalustaite was accepted by the Commission and was published by Holtstam et al. (2021). The mineral was found in very small amounts as a terrestrial alteration product of the iron meteorite Muonionalusta, Sweden.
Muonionalustaite is the natural analogue of synthetic Ni3Cl2(OH)4·4H2O (Bette et al., 2014) and the Ni-analogue of synthetic Mg3Cl2(OH)4·4H2O. The latter one is known as a component in magnesia cements (Sorel cements, Dinnebier et al., 2012). A comparison of natural and synthetic muonionalustaite and the Sorel cement phase is given in Table 1. The structure of muonionalustaite is built up of infinite triple chains of distorted edge-sharing NiO6 octahedra running along the b direction, with a partial replacement of O by Cl at the positions at the outher rims of the chains (bands). Between the chains, one-dimensional zig-zag chains of disordered Cl anions and water molecules are situated (Bette et al., 2014).
Mg3Cl2(OH)4·4H2O is a member of a series of magnesium hydroxide chloride hydrates with the general composition xMg(OH)2·yMgCl2·zH2O. In the Sorel cement nomenclature, the phases are named according to the ratio of x, y and z. The Mg analogue of muonionalustaite is then the 2-1-4 phase. Other phases like 3-1-8, 5-1-8, 2-1-2, 9-1-4 or 3-1-0 are known.
Interestingly, the formula of muonionalustaite represents from a pure chemical point, exactly the chloride analogue of the formula generally assumed for zaratite.
Figure 1. Green muonionalustaite with heazlewoodite from the Lord Brassey mine, Heazlewood district, Tasmania, Australia. Picture width 7 mm.
Figure 2. Muonionalustaite crystals from the Lord Brassey mine, Heazlewood district, Tasmania, Australia. SEM micrograph.
| Muonionalustaite,
Lord Brassey Mine, Tasmania |
Muonionalustaite,
Muonionalusta Meteorite |
Muonionalustaite,
synthetic |
Synthetic | |
| empirical formula | Ni3Cl1.92(OH)4.08·
nH2O |
(Ni2.88Fe0.02S0.02Al0.01Si0.01)
Cl2.27(OH)3.73·4H2O |
Ni3Cl2.1(OH)3.9·
4H2O |
Mg3Cl2(OH)4·
4H2O |
| crystal system | monoclinic | monoclinic | monoclinic | monoclinic |
| space group | C2/m | C2/m | C2/m | C2/m |
| a (Å) | 14.998 | 15.018 | 14.9575 | 15.1263 |
| b (Å) | 3.150 | 3.1490 | 3.1413 | 3.1707 |
| c (Å) | 10.485 | 10.502 | 10.4818 | 10.5236 |
| β (°) | 101.62 | 101.535 | 101.482 | 101.546 |
| V (Å3) | 485.23 | 486.62 | 482.50 | 494.508 |
| reference | this work | Holtstam et al., 2021 | Bette et al., 2014 | Dinnebier et al., 2012 |
Table 1. Crystallographic data for muonionalustaite and a related Sorel cement phase.
REFERENCES
Bette, S., Dinnebier, R.E. and Freyer, D. (2014): Ni3Cl2.1(OH)3.9·4H2O, the Ni Analogue to Mg3Cl2(OH)4·4H2O. Inorganic Chemistry 53, 4316-4324.
Bette, S., Dinnebier, R.E., Kremer, R.K. and Freyer, D. (2016): Ni3Cl2+X(OH)4-X·2H2O: structural, thermal, spectral, and magnetic properties in dependence of the chloride content. European Journal of Inorganic Chemistry, vol. 2016, issue 12, 1875-1885.
Dinnebier, R.E., Oestreich, M., Bette, S. and Freyer, D. (2012): 2Mg(OH)2·MgCl2·2H2O and 2Mg(OH)2·MgCl2·4H2O, Two High Temperature Phases of the Magnesia Cement System. Journal of Inorganic and General Chemistry (Zeitschrift für anorganische und allgemeine Chemie) 638, 626-633
Garcia-Guinea, J., La Iglesia, A., Crespo-Feo, E., González del Tánago, J. and Correcher, V. (2013): The status of zaratite: investigation of the type specimen from Cape Ortegal, Galicia, Spain. European Journal of Mineralogy 25, 995-1004.
Holtstam, D., Bindi, L., Karlsson, A., Söderhielm, J. and Zetterqvist, A. (2021): Muonionalustaite, Ni3(OH)4Cl2·4H2O, a new mineral formed by terrestrial weathering of the Muonionalusta iron (IVA) meteorite, Pajala, Norrbotten, Sweden. GFF 143, 1-7
Smith, J.L. and Brush, G.J. (1853): Reexamination of American minerals: Part II. Chesterlite; Loxoclase; Danbury feldspars; Haddam albite; Greenwood mica; Biotite; Margarodite; Chesterlite talc; Rhodophyllite; Cummingtonite; Hydrous Anthophyllite; Monrolite; Ozarkite; Dysyntribite; Gibbsite; Emerald nickel. American Journal of Science and Arts 16, 41-53