Zharchikhite, AlF(OH) 2 : a novel structure type related to α-PbO 2 .

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 P2 1 /c, a = 5.1788 (4), b = 7.8386 (4), c = 5.1624 (4) Å, β = 116.276 (10)°, V = 187.91 (3) Å 3 and Z = 4. Zharchikhite demonstrates a novel structure type roughly related to the α-PbO 2 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 AlF 2 (OH) 4 octahedra; adjacent chains are linked via F vertices and the pseudoframework contains wide channels.