Thermomagnetic analysis of magnetite parts of serpentinite samples and results of other investigations

Abstract

The normal type of serpentinites consists of chrysotile. The magnetite parts are essential parts of the structure of chrysotile serpentinites (primary magnetite). Chrysotile is changed to antigorite by mechanical deformations. The magnetite parts of rock structure are lost and they sat down in the veins of serpentinite rocks (secondary magnetite). In this paper the thermomagnetic diagrams and the results of X-ray investigations of secondary and primary magnetite are described. Some results of susceptibility measurements are given. The secondary magnetite is characterized by a region of oxydation in the interval 280–400° C (secondary magnetite→γ-Fe2O3→α-Fe2O3). The oxydation to α-Fe2O3 is remarkably. On the thermomagnetic diagrams of primary magnetite no typical oxydation region is to be seen. The oxydation: primary magnetite→α-Fe2O3 is very small. The interval of measured susceptibility values amounts to (10–1500)·10−6 cgs units. The essential variability of the main parts of serpentinite samples is characterized by the great changes of susceptibility values from point to point.