Cobalthydrogenarsenat‐Monohydrat. Darstellung und Kristallstruktur

Zettler, F. W.; Riffel, H.; Hess, H.; Keller, P.

doi:10.1002/zaac.19794540121

Cited by 14 publications

(2 citation statements)

References 7 publications

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“…The structure is considered isostructural with those of koritnigite (Keller et al, 1980) and cobaltkoritnigite (Zettler et al, 1979) The assignment of O sites as O, OH or H 2 O (OW) was straightforward based upon bondvalence considerations. Each of the four arsenate groups has one significantly longer AsÀO bond, which corresponds to an unshared tetrahedral vertex; the corresponding O atoms must correspond to OH groups because they cannot otherwise achieve bond-valence balance.…”

Section: Description Of the Structurementioning

confidence: 99%

Magnesiokoritnigite, Mg(AsO₃OH)·H₂O, from the Torrecillas mine, Iquique Province, Chile: the Mg-analogue of koritnigite

Kampf

Nash

Dini³

et al. 2013

Mineral. mag.

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The new mineral magnesiokoritnigite (IMA 2013-049), ideally Mg(AsO3OH)·H2O, was found at the Torrecillas mine, Salar Grande, Iquique Province, Chile, where it occurs as a secondary alteration phase in association with anhydrite, chudobaite, halite, lavendulan, quartz and scorodite. Crystals of magnesiokoritnigite are colourless to pale-pink, thin to thick laths up to 2 mm long. Laths are elongated on [001], flattened on {010} and exhibit the forms {010}, {110}, {10}, {101}, {031} and {01}. The crystals also occur in dense deep-pink intergrowths. Crystals are transparent with a vitreous lustre. The mineral has a white streak, Mohs hardness of ∼3, brittle tenacity, conchoidal fracture and one perfect cleavage on {101}. The measured and calculated densities are 2.95(3) and 2.935 g cm– 3, respectively. Optically, magnesiokoritnigite is biaxial (+) with α = 1.579(1), β = 1.586(1) and γ = 1.620(1) (measured in white light). The measured 2V is 50(2)° and the calculated 2V is 50°. Dispersion is r < v, medium. The optical orientation is Y ≈ b; Z ^ c = 36° in obtuse β (note pseudomonoclinic symmetry). The mineral is non-pleochroic. The empirical formula, determined from electron-microprobe analyses, is (Mg0.94Cu0.03Mn0.02Ca0.01)Σ 1.00As0.96O5H3.19. Magnesiokoritnigite is triclinic, P, with a = 7.8702(7), b = 15.8081(6), c = 6.6389(14) Å, α = 90.814(6), β = 96.193(6), γ = 90.094(7)°, V = 821.06(19) Å3 and Z = 8. The eight strongest X-ray powder diffraction lines are [dobs Å (I)(hkl)]: 7.96(100)(020), 4.80(54)(101), 3.791(85)(10,210,1,31), 3.242(56)(02,1,012), 3.157(92)(21,30,230), 3.021(61)(11,141,21,221), 2.798(41)(02,032) and 1.908(43)(multiple). The structure, refined to R1 = 5.74% for 2360 Fo > 4σF reflections, shows magnesiokoritnigite to be isostructural with koritnigite and cobaltkoritnigite.

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Section: Description Of the Structurementioning

confidence: 99%

Magnesiokoritnigite, Mg(AsO₃OH)·H₂O, from the Torrecillas mine, Iquique Province, Chile: the Mg-analogue of koritnigite

Kampf

Nash

Dini³

et al. 2013

Mineral. mag.

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“…No crystals were seen in the purple, compact gel. Therefore, cobaltkoritnigite was prepared by the procedure described by Zettler et al (1979). As specified therein, 0.33 g As 2 O 5 and 1.4 g CoSO 4 ⋅7H 2 O were mixed with 5 mL water and maintained in a Teflon-lined pressure bomb at 150°C for six days.…”

Section: Methodsmentioning

confidence: 99%

Thermodynamics and crystal structures of krautite, Mn[AsO₃(OH)]⋅H₂O, koritnigite, Zn[AsO₃(OH)]⋅H₂O and cobaltkoritnigite, Co[AsO₃(OH)]⋅H₂O

Majzlan

Plášil²,

Dachs³

2022

MinMag

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Synthetic samples of krautite, Mn[AsO 3 (OH)]•H 2 O, koritnigite, Zn[AsO 3 (OH)]•H 2 O, and cobaltkoritnigite, Co[AsO 3 (OH)]•H 2 O, were used for calorimetric experiments. For krautite and koritnigite, single-crystal X-ray diffraction was used to determine positions of all atoms, including the H atoms. These data allowed to determine the hydrogen-bond network and the function of H 2 O molecules in these structures. The structural formulae are Mn 4 (H 2 [3] O) 4 [AsO 3 (OH)] 4 and Zn 4 (H 2 [3] O) 2 [AsO 3 (OH)] 4 (H 2 [4] O) 2 , where [3] H 2 O and [4] H 2 O are the transformer and non-transformer H 2 O groups, respectively. Even though the principal features of these structures are identical, the details, especially those regarding the H 2 O groups, differ from a structure to another structure in this group. The solubility products (log K sp ) were determined from calorimetric data, that is, from the experimentally measured enthalpies of formation and entropies. They relate to the reaction M[AsO 3 (OH)]•H 2 O → M 2+ + HAsO 4 2-+ H 2 O and are -6.10 for krautite, -6.88 for koritnigite, and -6.83 for cobaltkoritnigite. We also estimated the log K sp for magnesiokoritnigite as -2.0. Calculation of phase diagrams shows that all these phases originate under acidic conditions from solutions with high metal and arsenate concentration.They are restricted to local environments, to pockets that maintain such high concentration over the time necessary for crystallization of the krautite-group phases.

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ChemInform Abstract: COBALT HYDROGENARSENATE MONOHYDRATE. PREPARATION AND CRYSTAL STRUCTURE

Zettler¹,

Riffel²,

Hess³

et al. 1979

Chemischer Informationsdienst

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Cobalthydrogenarsenat‐Monohydrat. Darstellung und Kristallstruktur

Cited by 14 publications

References 7 publications

Magnesiokoritnigite, Mg(AsO₃OH)·H₂O, from the Torrecillas mine, Iquique Province, Chile: the Mg-analogue of koritnigite

Magnesiokoritnigite, Mg(AsO₃OH)·H₂O, from the Torrecillas mine, Iquique Province, Chile: the Mg-analogue of koritnigite

Thermodynamics and crystal structures of krautite, Mn[AsO₃(OH)]⋅H₂O, koritnigite, Zn[AsO₃(OH)]⋅H₂O and cobaltkoritnigite, Co[AsO₃(OH)]⋅H₂O

ChemInform Abstract: COBALT HYDROGENARSENATE MONOHYDRATE. PREPARATION AND CRYSTAL STRUCTURE

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Cobalthydrogenarsenat‐Monohydrat. Darstellung und Kristallstruktur

Cited by 14 publications

References 7 publications

Magnesiokoritnigite, Mg(AsO3OH)·H2O, from the Torrecillas mine, Iquique Province, Chile: the Mg-analogue of koritnigite

Magnesiokoritnigite, Mg(AsO3OH)·H2O, from the Torrecillas mine, Iquique Province, Chile: the Mg-analogue of koritnigite

Thermodynamics and crystal structures of krautite, Mn[AsO3(OH)]⋅H2O, koritnigite, Zn[AsO3(OH)]⋅H2O and cobaltkoritnigite, Co[AsO3(OH)]⋅H2O

ChemInform Abstract: COBALT HYDROGENARSENATE MONOHYDRATE. PREPARATION AND CRYSTAL STRUCTURE

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Magnesiokoritnigite, Mg(AsO₃OH)·H₂O, from the Torrecillas mine, Iquique Province, Chile: the Mg-analogue of koritnigite

Magnesiokoritnigite, Mg(AsO₃OH)·H₂O, from the Torrecillas mine, Iquique Province, Chile: the Mg-analogue of koritnigite

Thermodynamics and crystal structures of krautite, Mn[AsO₃(OH)]⋅H₂O, koritnigite, Zn[AsO₃(OH)]⋅H₂O and cobaltkoritnigite, Co[AsO₃(OH)]⋅H₂O