Zincobotryogen, ZnFe³⁺(SO₄)₂(OH)•7H₂O

Author(s)

Zhuming Yang, Gerald Giester, Qian Mao, Yuguang Ma, Di Zhang, He Li

Abstract

Zincobotryogen occurs in the oxidation zone of the Xitieshan lead-zinc deposit, Qinghai, China. The mineral is associated with jarosite, copiapite, zincocopiapite, and quartz. The mineral forms prismatic crystals, 0.05 to 2 mm in size. It is optically positive (2Vcalc = 54.1°), with Z ? b and X ? c = 10°. The elongation is negative. The refractive indices are na = 1.542(5), nß = 1.551(5), n? = 1.587(5). The pleochroism scheme is X = colorless, Y = light yellow, Z = yellow. Microprobe analysis gave (in wt%): SO3 = 38.04, Al2O3 = 0.04, Fe2O3 = 18.46, ZnO = 13.75, MgO = 1.52, MnO = 1.23, H2O = 31.06 (by calculation), Total = 104.10. The simplified formula is (Zn,Mg)Fe3+(SO4)2(OH)·7H2O. The mineral is monoclinic, P121/n1, a = 10.504(2), b = 17.801(4), c = 7.1263(14) Å, and ß = 100.08(3)°, V = 1311.9(5) Å3, Z = 4. The strongest lines in the powder X-ray diffraction pattern d(I)(hkl) are: 8.92 (100)(110), 6.32 (77)(-101), 5.56 (23)(021), 4.08 (22)(-221),3.21 (31)(231), 3.03 (34)(032), 2.77 (22)(042). The crystal structure was refined using 2816 unique reflections to R1(F) = 0.0355 and wR2( F 2 ) = 0 . 0 6 5 1 . Th e r e f i n e d f o r m u l a i s (Zn0.84Mg0.16)Fe3+(SO4)2(OH)·7H2O. The atomic arrangement is characterized by chains with composition [Fe3+(SO4)2(OH)(H2O)]2- and ~ 7 Å repeat distance running parallel to the c-axis. The chain links to a [MO(H2O)5] octahedron (M = Zn, Mg) and an unshared H2O molecule, and forms a larger chain building module with composition [M2+Fe3+(SO4)2(OH)(H2O)6(H2O)]. The inter-chain module linkage involves only hydrogen bonding.

Organisation(s)

Department of Mineralogy and Crystallography

External organisation(s)

Chinese Academy of Sciences (CAS)

Journal

Mineralogy and Petrology

Volume

111

Pages

363-372

No. of pages

10

ISSN

0930-0708

DOI

https://doi.org/10.1007/s00710-016-0484-9

Publication date

11-2016

Peer reviewed

Yes

Austrian Fields of Science 2012

105116 Mineralogy, 105113 Crystallography

Keywords

ASJC Scopus subject areas

Geochemistry and Petrology, Geophysics

Portal url

https://ucrisportal.univie.ac.at/en/publications/d2559b97-66b5-49cd-9409-72c389aaa766