Studies have been done of the secondary chemico-viscous remanent magnetization (CVRM) produced in the oxidization and decomposition of high-purity crystal siderite specimens collected from Dalizi Deposit, Jilin Province. The CVRM intensity increases to a peak value at an annealing temperature of 490℃. The direction of CVRM is always parallel to the applied field, and no self-reversal behavior has been observed in the transformation of maghemite to hematite. It is suggested that the phase transition of magnetic minerals can make great contribution to secondary magnetization. Results of successive heating at low temperature indicate that the crystal mineral siderite is basically stable. Finally, the paleomagnetic significance of CVRM is discussed.
