Magnetic properties of Li 2 O–MnO 2 –CaO–P 2 O 5 –SiO 2 (LMCPS) glasses doped with various amounts of Fe 2 O 3 were investigated. There is a dramatic change in the magnetic property of pristine LMCPS after the addition of Fe 2 O 3 and crystallized at 850°C for 4h. Both the electron paramagnetic resonance and magnetic susceptibility measurements showed that the glass ceramic with 4at% Fe 2 O 3 exhibited the coexistence of superparamagnetism and ferromagnetism at room temperature. When the Fe 2 O 3 content was higher than 8at%, the LMCPS glasses showed ferromagnetism behavior. The complex magnetic behavior is due to the distribution of (Li, Mn)ferrite particle sizes driven by the Fe 2 O 3 content. The thermal induced hysteresis loss of the crystallized LMCPS glass ceramics was characterized under an alternating magnetic field. The energy dissipations of the crystallized LMCPS glass ceramics were determined by the concentration and Mn/Fe ratios of Li(Mn, Fe)ferrite phase formed in the glass ceramics.