Nice coloured crystals of indialite (~0.5 mm long) with pseudobrookite in a vug of a clay-xenolith.
Volker Betz’s Photo
Indialite – the Mg analogue of ferroindialite. Hexagonal high-temperature dimorph of cordierite (orthorhombic-pseudohexagonal). The mineral has been assigned to the beryl group. Anthropogenic since it was formed as the result of fusion and recrystallization of sedimentary rocks above burning coal seams. It was subsequently found in nature in hornfels and rapidly quenched volcanic rocks.