Tschörtnerite, a copper-bearing zeolite from Bellberg volcano, Eifel, Germany
- Author(s)
- Herta Silvia Effenberger, Gerald Giester, Werner Krause, Heinz-Jürgen Bernhardt
- Abstract
The new mineral tschortnerite, ideally Ca4(K,Ca,Sr,Ba)3Cu3(0H)8[Si12Al1204S]·ϰH20, ϰ > 20, occurs as well-formed cubes up to a maximum size of 0.15 mm in a Ca-rich xenolith at the Bellberg volcano near Mayen, Eifel, Germany. The light blue, transparent crystals are optically isotropic, n = 1.504(2). Microprobe analysis (in weight percent) gave CaO 13.10, CuO 9.64, SrO 4.49, BaO 1.93, K2O 1.37, Fe2O3 0.30, Al2O3 25.21, SiO2 30.25, H2O (calc, by difference) 13.71. The empirical formula based on 48 O atoms within the tetrahedral net is Ca5.60Sr1.04K0.70Ba0.30Cu2.90Fe0.09Al11.85Si12.06O48(OH)8.44·14.01H2O. Tschörtnerite is cubic, space group Fm3̅m [a = 31.62(1) Å, V = 31614 Å3, Z = 16]. The density is -Dmeas = 2.1 g/cm3, Dcalc = 2.10 g/cm3. Single-crystal X-ray investigations showed that tschortnerite is a zeolite; the structure contains interconnection of double six-rings, double eight-rings, sodalite cages, truncated cubo-octahedra, and previously unknown 96-membered cages (tschörtnerite cage). A new structural unit is the [Cu12(OH)2JCa8O24(H2O)8 cluster centered within the truncated cubo-octahedron. The cluster is formed by a rhomb- dodecahedron-like arrangement of comer connected CuO4 squares, the eight CaO7 poly- hedra are branched. The sodalite cage houses Ca4(OH)4O12 clusters of edge-sharing CaO6 octahedra. Half-occupied (K,Ca,Sr,Ba) positions were located in the basal and top face of the double eight-rings, i.e., the border to the tschortnerite cage. Within the large tschortnerite cage only H2O molecules were localized.
- Organisation(s)
- Department of Mineralogy and Crystallography
- External organisation(s)
- Ruhr-Universität Bochum (RUB)
- Journal
- The American mineralogist
- Volume
- 83
- Pages
- 607-617
- No. of pages
- 11
- ISSN
- 0003-004X
- DOI
- https://doi.org/10.2138/am-1998-5-620
- Publication date
- 06-1998
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 105113 Crystallography, 105116 Mineralogy
- Portal url
- https://ucrisportal.univie.ac.at/en/publications/tschoertnerite-a-copperbearing-zeolite-from-bellberg-volcano-eifel-germany(e4ae3959-e036-4b38-a584-3243a2b19125).html