Cymrite

Cymrite is a silicate mineral with the chemical formula BaAl₂Si₂(O,OH)₈·H₂O. The mineral is named for Cymru, which is the Welsh word for Wales.

Cymrite, with perfect cleavage and a monoclinic crystalline system, falls in the silicate group. Silicates are formed of Silicon and Oxygen bonding together to form tetrahedra. The symmetry of Cymrite is classified as having a mirror plane. It has a moderate relief, meaning the contrast between the mineral and the epoxy of a thin section makes cymrite easily visible. The birefringence of the mineral is 0.01. Cymrite, being monoclinic is anisotropic with two optic axes.