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@article{1847132,
author = {Vrtiška, Luboš and Tvrdý, Jaromír and Plášil, Jakub and Sejkora, Jiří and Škoda, Radek and Chukanov, Nikita V. and Massanek, Andreas and Filip, Jan and Dolníček, Zdeněk and Veselovský, František},
article_number = {2},
doi = {http://dx.doi.org/10.5194/ejm-34-223-2022},
keywords = {beraunite; eleonorite; discreditation; electron microprobe analysis; single-crystal X-ray diffraction; Raman spectroscopy; Mössbauer spectroscopy; Hrbek mine; Svatá Dobrotivá; Czech Republic},
language = {eng},
issn = {0935-1221},
journal = {European Journal of Mineralogy},
title = {Redefinition of beraunite, Fe3+6(PO4)4O(OH)4 ⋅ 6H2O, and discreditation of the name eleonorite: a re-investigation of type material from the Hrbek Mine (Czech Republic)},
url = {http://ejm.copernicus.org/articles/34/223/2022/},
volume = {34},
year = {2022}
}
TY - JOUR
ID - 1847132
AU - Vrtiška, Luboš - Tvrdý, Jaromír - Plášil, Jakub - Sejkora, Jiří - Škoda, Radek - Chukanov, Nikita V. - Massanek, Andreas - Filip, Jan - Dolníček, Zdeněk - Veselovský, František
PY - 2022
TI - Redefinition of beraunite, Fe3+6(PO4)4O(OH)4 ⋅ 6H2O, and discreditation of the name eleonorite: a re-investigation of type material from the Hrbek Mine (Czech Republic)
JF - European Journal of Mineralogy
VL - 34
IS - 2
SP - 223-238
EP - 223-238
PB - Copernicus GmbH
SN - 09351221
KW - beraunite
KW - eleonorite
KW - discreditation
KW - electron microprobe analysis
KW - single-crystal X-ray diffraction
KW - Raman spectroscopy
KW - Mössbauer spectroscopy
KW - Hrbek mine
KW - Svatá Dobrotivá
KW - Czech Republic
UR - http://ejm.copernicus.org/articles/34/223/2022/
N2 - Re-investigation of the type material of beraunite from the Hrbek Mine, Svata Dobrotiva, Czech Republic, proved the identity of beraunite and eleonorite. Based on this study, the mineral eleonorite was discredited, and the ideal formula of beraunite was redefined from Fe2+Fe53+(PO4)(4)O(OH)(5)center dot 6H(2)O to Fe-6(3+)(PO4)(4)O(OH)(4)center dot 6H(2)O. Beraunite from Hrbek Mine usually forms prismatic crystals flattened on {100}; elongated along b axis, striated on {100} parallel to b, up to 0.2 x 0.5 x 3 mm, often in radial clusters up to 6 mm in size in association with black goethite, olive-green to dark green dufrenite and yellow to orange cacoxenite. Beraunite is hyacinth red, dark red, or red-brown and has a light orange-red streak; crystals are translucent, with a vitreous luster. The symmetry of the structure was found to be lower (Cc) than reported in the past (C2/c); this has been proven by the crystal structure refinement, R-obs = 2.7 % for Cc and similar to 8 % for C2/m. Refined unit-cell parameters obtained from powder X-ray diffraction data of the original material of Friedrich August Breithaupt are a = 20.653(2), b = 5.1433(6), c = 19.241(2) angstrom, beta =93.560(9)degrees, and V = 2039.9(2) angstrom(3). Calculated density is 2.961 g cm(-3). Beraunite is optically biaxial (+), alpha = 1.768(2), beta = 1.781(3), gamma >1.805, 2V(meas) = 69(4)degrees, and 2V(calc) is not possible to calculate. Dispersion of optical axes is strong, r >v. The orientation is Y = b, X approximate to a, and Z approximate to c. Pleochroism is strong; Z (brown-red) >> Y >X (both brownish yellow). The empirical formula of the original beraunite sample calculated on the basis of P = 4 apfu is (Fe5.763+Al0.15Zn0.01)(5)(.92)(PO4)(4.00)O-0.99(OH)(3.77) center dot 6H(2)O. The Fe-57 Mossbauer spectrum of beraunite neotype (National Museum, Prague) from type locality implies that all iron atoms in beraunite structure are exclusively trivalent, located at the M site with different next-nearest-neighbor configurations. There is no spectral evidence for Fe2+ or iron in some impurities (e.g., limonite).
ER -
VRTIŠKA, Luboš, Jaromír TVRDÝ, Jakub PLÁŠIL, Jiří SEJKORA, Radek ŠKODA, Nikita V. CHUKANOV, Andreas MASSANEK, Jan FILIP, Zdeněk DOLNÍČEK a František VESELOVSKÝ. Redefinition of beraunite, Fe3+6(PO4)4O(OH)4 ⋅ 6H2O, and discreditation of the name eleonorite: a re-investigation of type material from the Hrbek Mine (Czech Republic). \textit{European Journal of Mineralogy}. Copernicus GmbH, 2022, roč.~34, č.~2, s.~223-238. ISSN~0935-1221. Dostupné z: https://dx.doi.org/10.5194/ejm-34-223-2022.
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