Chvaleticeite is a

monoclinic In crystallography, the monoclinic crystal system is one of the seven crystal systems. A crystal system is described by three Vector (geometric), vectors. In the monoclinic system, the crystal is described by vectors of unequal lengths, as in t ...

hexahydrite

manganese Manganese is a chemical element; it has Symbol (chemistry), symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. Manganese was first isolated in the 1770s. It is a transition m ...

magnesium Magnesium is a chemical element; it has Symbol (chemistry), symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 ...

sulfate mineral The sulfate minerals are a class of minerals that include the sulfate ion () within their structure. The sulfate minerals occur commonly in primary evaporite depositional environments, as gangue minerals in hydrothermal Vein (geology), veins and as ...

with formula: (Mn²⁺, Mg) O₄�6(H₂O). It occurs in the oxidized zone of manganese silicate deposits with pyrite and rhodochrosite that have undergone regional and contact metamorphism. It is defined as the manganese dominant member of the hexahydrite group. Chvaleticeite is named after the city Chvaletice,

Bohemia Bohemia ( ; ; ) is the westernmost and largest historical region of the Czech Republic. In a narrow, geographic sense, it roughly encompasses the territories of present-day Czechia that fall within the Elbe River's drainage basin, but historic ...

, in the

Czech Republic The Czech Republic, also known as Czechia, and historically known as Bohemia, is a landlocked country in Central Europe. The country is bordered by Austria to the south, Germany to the west, Poland to the northeast, and Slovakia to the south ...

. Chvaleticeite and minerals like it have been studied for their

hydrogen bonding In chemistry, a hydrogen bond (H-bond) is a specific type of molecular interaction that exhibits partial covalent character and cannot be described as a purely electrostatic force. It occurs when a hydrogen (H) atom, Covalent bond, covalently b ...

and incongruent melting properties as they are predicted to form in the relative environments of Mars and other bodies in the

Solar System The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Sola ...

Structure

The structure in chvaleticeite is made by

in metallic sulfates. Due to the minute grain size of chvaleticeite, typical single crystal methods could not be used. Through analogy with hexahydrite the Guinier powder diffraction method was used to identify the following structural parameters: space group C 2/c, a = 10.05(2) Å, b = 7.24(2) Å, c = 24.3(1) Å; β = 98.0(2)°, V = 1754 Å³, Z = 8, Dx = 1.84 g·cm⁻³; a : b : c = 1.3881 : 1 : 3.3564.

Composition

Chvaleticeite has an empirical formula of (Mn²⁺, Mg) O₄�6(H₂O) and is a member of the hexahydrite group with the space group C2/c. Chemical analysis was carried out using classical chemical methods. Sulfate was determined gravimetrically, MnO was determined using titration, MgO was determined by EDTA titration and CaO, Fe₂O₃, K₂O and Na₂O using AAS. The H₂O was determined by the modified Penfield method. The performed analysis produced the following result: MnO 15.81, MgO 6.41, CaO 0.04, FeO traces, Fe₂O₃ 0.10, Al₂O₃ traces, K₂O 0.005, Na₂O 0.011, SO₃ 31.48, P₂O₅ traces, H₂O+ 0.37, H₂O- 45.22, insoluble residue 0.36, sum 99.81 weight percent.

Occurrence

Chvaleticeite was discovered in a sulfate paragenesis in the

oxidation Redox ( , , reduction–oxidation or oxidation–reduction) is a type of chemical reaction in which the oxidation states of the reactants change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is ...

zone of the Upper Proterozoic volcanogenic massive sulfide ore deposit of pyrite-manganese ores at Chvaletice. It was found in association with

melanterite Melanterite is a mineral form of hydrous iron(II) sulfate: FeSO4·7H2O. It is the iron analogue of the copper sulfate chalcanthite. It alters to siderotil by Dehydration, loss of water. It is a secondary sulfate mineral which forms from the oxida ...

(it can form by partial dehydration), Mg- jokouite, Mg- ilesite, rozenite, copiapite and gypsum. This paragenesis allows heptahydrates and tetrahydrates to dominate over pentahydrates and hexahydrates. Chvaleticeite is completely soluble in water.

References

{{Reflist * Bauer, W.H. (1962) Zur Krisallchemie der Salzhydrate. Die Kristallstrukturen von (Mn, Mg)SO4x6H2O(Leonhardit) und FeSO4x4H2O(Rozenit). Acta Crystallogr., 15, 815-826. * Bernard, J.H. et al. (1981) Petrology and geochemistry of the Upper Proterozoic Fe-Mn deposits Chvaletice, Mineralogie Ceskoslovenska – 2nd ed., Academia, Praha. Chab, J. et al. (1986)(Bohemia, Czechoslovakia). – Sbor. Geol. Ved, Lozisk. Geol. Miner., 23 118 69, Praha. * Blake, A., Cooke, P., Hubberstey, P., and Sampson, C. (2001) Zinc(II) sulphate tetrahydrate. Acta Crystallographica E, 57, i109–i111. * Jennifer L. Anderson et al. (2012) The atomic structure of deuterated boyleite ZnSO4·4D2O, ilesite MnSO4·4D2O, and bianchite ZnSO4·6D2O, American Mineralogist Volume 97, 1905–1914. * Kellersohn, T. (1992) Structure of Cobalt Sulfate Tetrahydrate. Acta Crystallogr. C48, 776±779. * Palache, C., H. Berman, and C. Frondel (1951) Dana’s system of mineralogy, (7th edition), II, 486-487. *Petr Ondrus, Frantiesk Veselovsky, Jan Hlousek. Et al (1997) Secondary minerals of the Jachymov (Joachimsthal) ore district: Journal of the Czech Geological Society., 12 16 17 18. * R.C. Peterson et al. (2007) Meridianiite: A new mineral species observed on Earth and predicted to exist on Mars, American Mineralogist Volume 92, 1756-1759. Sulfate minerals Monoclinic minerals Minerals in space group 15