The relationship between the magnetic properties of terrestrial igneous rocks and the composition and internal structure of their component Fe-oxide grains

Summary. Hysteresis loops and the demagnetization of saturation remanence (SIRM), before and after heating, are used to determine the high field magnetic behaviour and the coercivity spectra for common igneous rock types containing discrete types of magnetic carriers. These incude homogeneous to highly exsolved titanomagnetite grains, oxidized titanomagnetite grains (martite), exsolved hemo-ilmenite grains, and oxidized ilmenite grains. Specific internal structures and changes in composition due to oxidation are found to have characteristic effects on both high and low field magnetic properties.