  We observe a considerable hysteresis effect of low-field microwave absorption
(LFMA) in copper-substituted lead apatite. By continuously rotating samples
under external magnetic field, this effect is diminished which can not be
renewed by a strong magnetic field but will be spontaneously recovered after
two days, indicating its glassy features and excluding possibility of any
ferromagnetism. The intensity of LFMA is found to sharply decrease at around
250K, suggesting a phase transition takes place. A lattice gauge model is then
employed to assign these effects to the transition between superconducting
Meissner phase and vortex glass, and the slow dynamics wherein is calculated as
well.
