Almarudite

Almarudite (IMA symbol: Alr ) is an extremely rare alkaline manganese beryllium silicate mineral of the cyclosilicates (ring silicates) class, with the chemical formula K([ ],Na)2(Mn^{2+},Fe^{2+},Mg)2(Be,Al)3[Si12O30], from the volcanic environment of the Eifel Mountains in Germany.