Zharchikhite, AlF(OH)₂: a novel structure type related to a-PbO2

The crystal structure of zharchikhite, AlF(OH)(2), from the Zharchikhinskoe deposit (Buryatia, Russia) is solved here using single-crystal X-ray diffraction. The mineral is monoclinic, space group P21/c, a = 5.1788 (4), b = 7.8386 (4), c = 5.1624 (4) A degrees, = 116.276 (10), V = 187.91 (3) A degrees 3 and Z = 4. Zharchikhite demonstrates a novel structure type roughly related to the-PbO2 structure type and different from other compounds of the Al-F-OH system. The crystal structure of zharchikhite is based on the octahedral pseudoframework built from zigzag chains of edge-sharing AlF2(OH) 4 octahedra; adjacent chains are linked via F vertices and the pseudoframework contains wide channels.