Goldhillite, Cu₅Zn(AsO₄)₂(OH)₆·H₂O, a new mineral species, and redefinition of philipsburgite, Cu₅Zn[(AsO₄)(PO₄)](OH)₆·H₂O, as an As-P ordered species

Autor(en)

Rezeda M. Ismagilova, Branko Rieck, Anthony R. Kampf, Gerald Giester, Elena S. Zhitova, Christian L. Lengauer, Sergey V. Krivovichev, Andrey A. Zolotarev, Justyna Ciesielczuk, Julia A. Mikhailova, Dmitry I. Belakovsky, Vladimir N. Bocharov, Vladimir V. Shilovskikh, Natalia S. Vlasenko, Barbara P. Nash, Paul M. Adams

Abstrakt

Philipsburgite has been redefined as the intermediate member of the goldhillite–philipsburgite–kipushite isomorphous series with the ideal formula Cu₅Zn[(AsO₄ )(PO₄)](OH)₆⋅H₂O due to the site-selective As–P substitution. The new mineral goldhillite, ideally Cu₅Zn(AsO₄)₂(OH)₆⋅H₂O [or Cu₅Zn(AsO₄)(AsO₄ )(OH)₆⋅H₂O], is the arsenate end-member of this series. Goldhillite occurs on fracture sur-
faces in a rock comprised mostly of quartz with iron hydroxides in association with mixite, cornwallite and conichalcite. Goldhillite forms transparent, bright emerald-green, tabular crystals with vitreous lustre, flattened on {100}, up to 1 mm across and in rosettes up to 1.5 mm. The mineral is brittle with uneven fracture and perfect cleavage on {100}; the Mohs hardness is 3.5. The calculated density for the holotype is 4.199 g cm^–3 . The Raman spectrum is consistent with the presence of H 2 O-molecules, OH-groups, AsO 4 tetrahedra and traces of PO₄. Electron microprobe analyses of goldhillite (H₂O content based on the crystal structure) provided: CuO 48.91, ZnO 13.18, As₂O₅ 26.06, P₂O₅ 3.25, H₂O 8.97, total 100.37 wt.%. The empirical formula for goldhillite based on O = 15 apfu is (Cu_4.69Zn_1.23 )_Σ5.92(As_0.86P_0.18O₄)₂(OH)_5.61⋅H₂O. The crystal structures of goldhillite and philipsburgite were determined using single-
crystal X-ray diffraction data and refined to R1 = 0.054 (for 2365 I > 2σI reflections) and 0.052 (for 2308 I > 2σI reflections), respectively. Goldhillite is monoclinic, P21/c, a = 12.3573(5), b = 9.2325(3), c = 10.7163(4) Å, β = 97.346(4)°, V = 1212.59(8) ų and Z = 4. Philipsburgite is monoclinic, P21/c, a = 12.3095(9), b = 9.2276(3), c = 10.7195(3) Å, β = 97.137(7)°, V = 1208.16(10) ų and Z = 4. The strongest lines of the powder X-ray diffraction pattern of goldhillite [d, Å (I, %)(hkl)] are: 4.09 (28)(300), 3.41 (23)(12 -2, 221, 311), 2.57 (100)(132, 11 -4, 20 -4), 2.17 (18)(42 -3, 332), 1.95 (22)(432) and 1.54 (20)(13 -6, 060). Goldhillite is named after its type locality, the Gold Hill mine, Tooele County, Utah, USA.

Organisation(en)

Institut für Mineralogie und Kristallographie

Externe Organisation(en)

Saint Petersburg State University, Natural History Museum of Los Angeles County, Russian Academy of Sciences, University of Silesia in Katowice, University of Utah

Journal

Mineralogical Magazine

Band

86

Seiten

436-446

Anzahl der Seiten

11

ISSN

0026-461X

DOI

https://doi.org/10.1180/mgm.2022.36

Publikationsdatum

06-2022

Peer-reviewed

Ja

ÖFOS 2012

104026 Spektroskopie, 105116 Mineralogie, 105113 Kristallographie

Schlagwörter

ASJC Scopus Sachgebiete

Geochemistry and Petrology

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/ab33f233-30c6-4c37-8c1e-b0283de3f94b