Katsarosite Zn(C₂O₄)·2H₂O, a new humboldtine-group mineral from the Lavrion Mining District, Greece

Autor(en)

Gerald Giester, Branko Rieck, Christian Lengauer, Uwe Kolitsch, Lutz Nasdala

Abstrakt

Katsarosite, ideally Zn(C2O4)·2H2O, named for Īraklīs Katsaros, is a new mineral found at the Esperanza Mine in the Kaminiza area of the Lavrion Mining District, Greece. Katsarosite usually occurs directly on sphalerite or embedded in jarosite and/or hydrozincite, often intimately intergrown with gypsum and overgrown by goslarite and/or epsomite. Crystal aggregates are mostly fine granular to earthy, with individual crystals being usually rounded with an average diameter of 30 µm, sometimes prismatic along [001] or platy, exhibiting the indistinct forms {100}, {001}, {110}, and {101}. Katsarosite is malleable with a Mohs hardness of 1½ – 2 and exhibits a perfect cleavage on {110}; the fracture is uneven in all other directions. The colour depends on the iron (Fe²⁺) content, ranging from pure white in almost Fe-free samples to yellow in Fe-rich specimens. It has a resinous luster and a white streak; no luminescence has been observed under either short- or long-wave ultraviolet radiation. Katsarosite is optically biaxial (+). Refractive indices measured at a wavelength of 589 nm are n_α=1.488(2), n_β=1.550(2), n_γ=1.684(2), with 2V_obs=71(3)°. Chemical analysis gave on average C₂O₃ 38.32 wt%, ZnO 38.99 wt%, FeO 1.92 wt%, and H₂O 19.04 wt% (the latter was deduced based on the crystal-structure refinement), with traces
of MgO and MnO. The new mineral is readily soluble in dilute acids. Katsarosite is monoclinic, space group C2/c, with unit-cell parameters a=11.768(3), b=5.3882(12), c=9.804(2) Å, β=127.045(8)°, V=496.2(2) Å3 (Z=4). The strongest lines in the Gandolfi X-ray powder pattern [dobs in Å, I_obs/I₁₀₀, (hkl)] are: 4.6745, 100, (200); 4.7678, 94, (202); 2.9533, 51, (402); 4.7030, 37, (1 1 1); 3.9266, 33, (002); 3.5686, 27, (111); 2.6574, 22, (1 1 3); 3.5992, 8, (1 1 2); 2.7032, 4, (020). The crystal structure was refined based on single-crystal X-ray diffraction data to R(F)=0.08. The observed mass density of 2.50(2) g cm⁻³ compares well with the calculated value (2.508 g cm⁻³). Katsarosite belongs to the humboldtine group, whose crystal-structure type is well described for both isotypic minerals and synthetic compounds in the literature. The atomic arrangement in Zn(C₂O₄)·2H₂O is characterized by chains consisting of isolated ZnO₆ octahedra which are alternately linked along [010] via oxalate anions. These chains are interconnected through hydrogen bonds only, with Ow···O (with Ow denoting the O atom of the H₂O molecule) donor–acceptor distances of~2.8 Å.

Organisation(en)

Institut für Mineralogie und Kristallographie

Externe Organisation(en)

Naturhistorisches Museum Wien (NHM)

Journal

Mineralogy and Petrology

Band

117

Seiten

259-267

Anzahl der Seiten

9

ISSN

0930-0708

DOI

https://doi.org/10.1007/s00710-023-00810-9

Publikationsdatum

2023

Peer-reviewed

Ja

ÖFOS 2012

104026 Spektroskopie, 105116 Mineralogie, 105113 Kristallographie

Schlagwörter

ASJC Scopus Sachgebiete

Geochemistry and Petrology, Geophysics

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/15075b77-0a4a-4a72-91e3-190d3fc65638