The crystal structure of kassite, ideally Ca[Ti2O4(OH)2], containing 2 wt% Cr2O3, from the Saranovskoye chromite deposit, Perm’ district, Northern Urals, has been determined and refined to R1 = 0.06 using single crystal X-ray diffraction data. The crystals have monoclinic symmetry, P21/a, with a = 5.275(1), b = 9.009 (2), c = 9.557 (2) Å, β = 90.43°. A pronounced sub-structure for the mineral, conforming to space group I2/a, is related to the I2/a structure for lucasite-(Ce), Ce[Ti2O5(OH)]. It comprises (001) layers of gibbsite-like fused hexagonal rings of edge-shared Ti(O,OH)6 octahedra with the Ca atoms sandwiched between pairs of opposing rings and displaced from the center of the rings along [010]. Ordering of the protons in chromian kassite lowers the symmetry to P21/a. Kassite, CaTi2O4(OH)2, and cafetite, CaTi2O5(H2O), are identical chemically but significantly different in their crystal structures.

You do not have access to this content, please speak to your institutional administrator if you feel you should have access.