Energy level diagram, Monoclinic, Transitional

• Er-La-O-V-Yb
• Er-O-Si-Tm-Y-Yb
• Al-K-Mn-O-Sr
• Al-Mn-Na-O-Sr
• Al-Li-Mn-O-Sr
• transitional
• chalcogen
• rare earth
• luminescent
• lanthanoid