2c and displays HC behaviour typical of SD or small
PSD magnetite [7], i.e., on warming HC drops at 15K, until the Verwey transition, followed by a
gradual drop from 16 to 13 mT on warming to room temperature; such behaviour has been previously
predicted [8]. The FORC diagram of Fig. 2d was measured at 15 K after ZFC and exhibited behaviour
characteristic of SD grains displaying moderate inter-particle magnetostatic interactions [9].