Bechererite, (Zn,Cu)6Zn2(OH)13[(Si,S)(O,OH)4]2, a novel mineral species from the Tonopah-Belmont mine, Arizona
- Author(s)
- Gerald Giester, Branko Rieck
- Abstract
Bechererite is a new mineral found on dump material from the Tonopah-Belmont mine, Maricopa County, Arizona. It occurs as thin elongated crystals, commonly in hemispherical aggregates, and it is assocd. with rosasite, hydrozincite, willemite, smithsonite, paratacamite, and boleite. Bechererite is light green, transparent with vitreous luster, and has perfect cleavage parallel to {001}. It has a d. of 3.45(5) g/cm3 and a Mohs hardness of 2-3. Optically, it is uniaxial (-) with epsilon = 1.611(1) and omega = 1.705(1). The empirical formula (based on 21 O atoms) is (Zn4.93Cu1.01)Zn2(OH)13(S1.10Si0.95)[O5.30(OH)2.70], simplified to (Zn,Cu)6Zn2(OH)13[(S,Si)(O,OH)4]2. The strongest lines in the x-ray powder diffraction pattern are [dobs (.ANG.)(Iobs,hkl)] 7.37(100,001), 3.623(25,11.hivin.1), 3.282(30,012), 2.724(30,120), 2.556(50,121), and 1.572(20,410). The crystal structure was solved by direct methods and refined to R = 0.041 on the basis of single-crystal x-ray diffraction data of 281 unique reflections up to (sin q)/lamda = 0.48 .ANG.-1 [space group P.hivin.3, a = 8.319(2), c = 7.377(3) .ANG., V = 442.1(1) .ANG.3, Z = 1]. The at. arrangement of bechererite is characterized by sheets of edge-sharing octahedra with ordered vacancies, interconnected by Zn2O7 groups. Isolated XO4 tetrahedra (X = S, Si) share a common corner with one O atom of the octahedral sheet. A complex system of hydrogen bonds occurs in bechererite.
- Organisation(s)
- Department of Mineralogy and Crystallography
- Journal
- The American mineralogist
- Pages
- 244 - 248
- No. of pages
- 5
- ISSN
- 0003-004X
- DOI
- https://doi.org/10.2138/am-1996-1-230
- Publication date
- 1996
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 105116 Mineralogy, 105113 Crystallography
- Portal url
- https://ucrisportal.univie.ac.at/en/publications/c17805f7-131e-46a7-8669-1e57ec09e8b4