Abstract
The first part of this paper describes the investigation of thermomagnetic effects in three basalt samples. It was found that when a sample was heated in air the ferrimagnetic mineral component changed from a homogeneous member of the Ulvöspinell-Magnetite-series into two components. One of these had the same O/Fe-ratio, the other one the same Fe/Ti-ratio as the original mineral. No changes took place when the sample was heated in a vacuum of 10-5 Torr.
The second part deals with the observation of domain patterns in natural magnetites and the changes of these patterns under the influence of external magnetic fields. With the help of a new polishing technique powder patterns could be observed on magnetite grains in a non-conducting rock matrix.
In the third part the magnetization of the Suevites-that are tuffaceous rocks formed in connection with the formation of the Ries crater-is discussed. At all locations investigated the magnetization is nearly anti-parallel to the present direction of the earth's magnetic field. The small scatter among the directions from different location is taken as an indication for simultaneous magnetization of all Suevites.
