Abstract
The crystal structures of three different solid-solution members between the new mineral oxyvanite (V3O5) – and berdesinskiite (V2TiO5) from a quartzite rock in the Pereval marble quarry of the Sludyanka complex, south of Lake Baikal (Russia), have been refined in space group C2/c (a ≈ 10.0, b ≈ 5.0, c ≈ 7.0 Å, β ≈ 111°) from X-ray single-crystal diffraction-data. The composition of the studied crystals, determined by electron-microprobe analyses, is: (V1.673+Cr0.333+)(V0.594+Ti0.414+)O5, (V1.673+Cr0.333+)(V0.464+Ti0.544+)O5, and (V1.383+Cr0.613+)(V0.244+Ti0.764+)O5. The common structure type of oxyvanite and berdesinskiite can be described by hexagonal closest oxygen packing with 3/5 of the octahedral voids occupied. Site-occupancy refinements support previous studies on synthetic V2TiO5 and V3O5 indicating that a strongly distorted octahedrally coordinated site, forming pairs of face-sharing octahedra, is 1:1 occupied by M3+ and M4+ (Ti4+, V4+) whereas a more regular octahedral site is only occupied by M3+ (V, Cr).