7 sites (52 cores in total) were collected from the sandstone of J3-K1 which as an overlying formation on the coal field has outcropped at the Pingzhuang, Inner Mongolia, China. Noticeable and unusual changes in susceptibility, magnetic remanence, IRM curve, viscous re-manence as well as magnetic fabric have been found after some steps of thermal demagnetization although these specimens were originally associated with fairly weak remanence and low susceptibility (mean values:J0=5×10-3A/m; K = 60×10-5 (SI). ...