The crystal structure of gatehouseite

作者：Elliott P^*; Pring A

来源：Mineralogical Magazine, 2011, 75(6): 2823-2832.

DOI：10.1180/minmag.2011.075.6.2823

• gatehouseite
• manganese
• phosphate
• crystal structure

The crystal structure of the manganese phosphate mineral gatehouseite, ideally Mn(5)(2+)(PO(4))(2)(OH)(4), space group P2(1)2(1)2(1), a = 17.9733(18), b = 5.6916(11), c = 9.130(4) angstrom, V = 933.9(4) angstrom(3), Z = 4, has been solved by direct methods and refined from single-crystal X-ray diffraction data (T = 293 K) to an R index of 3.76%. Gatehouseite is isostructural with arsenoclasite and with synthetic Mn(5)(2+)(PO(4))(2)(OH)(4). The structure contains five octahedrally coordinated Mn sites, occupied by Mn plus very minor Mg with observed < Mn-O > distances from 2.163 to 2.239 angstrom. Two tetrahedrally coordinated P sites, occupied by P, Si and As, have < P-O > distances of 1.559 and 1.558 angstrom. The structure comprises two types of building unit. A strip of edge-sharing Mn(O,OH)(6) octahedra, alternately one and two octahedra wide, extends along [010]. Chains of edge- and corner-shared Mn(O,OH)(6) octahedra coupled by PO(4) tetrahedra extend along [010]. By sharing octahedron and tetrahedron corners, these two units form a dense three-dimensional framework, which is further strengthened by weak hydrogen bonding. Chemical analyses by electron microprobe gave a unit formula of (Mn(4.99)Mg(0.02))(Sigma 5.01)(P(1.76)Si(0.20)As(0.07))(Sigma 2.30)O(8)(OH)(3.97).

• 出版日期2011-12