The Pseudobrookite Group: Crystal Chemical Features of the Armalcolite Fe2+ Analogue.

The crystal structure of a potentially new mineral, the Fe2+-dominant analogue of armalcolite with the idealized formula Fe2+Ti2O5 has been solved. The sample studied originates from a pneumatolytic association related to the lamproite complex of SE Spain. The mineral is orthorhombic, space group Cmcm, the unit-cell parameters are a = 3.7325(1) Å, b = 9.7649(4) Å, c = 9.9902(3) Å, V = 364.12(2) Å3. The crystal-chemical formula (Z = 4) is in good agreement with the chemical composition of the mineral. [ABSTRACT FROM AUTHOR]