1) Monoclinic mineral 
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 ...