In the present paper, magnetic contribution on the aggregation of some magnetic mineral particle ultrafines were studied. There are two different magnetic properties that may enhance particle aggregation: a) field-induced magnetic moment; and b) magnetic moment due to the remanent magnetisation. The magnetic field-induced aggregation of the oxide mineral particle ultrafines (hematite and chromite) in aqueous suspension at moderate ionic strenght was investigated using a labortory scale electromagnetic solenoid. The experimental results relate the aggregation process (as determined by magneto-sedimentation analysis) to particle size and the external magnetic field in the antural pH value of the dispersions by using a modified form of the DLVO theory. In cases where the electrostratic repulsion was not suppressed, then the long range magnetic forces enabled aggregation to occur in the "secondary minimum" potential energy sink. This caused the formation of chains/rings, which appeared to be relatively stable at enhanced rates of settling. It is indicated in this paper that hematite ultrafines in a well-dispersed slurry are selectively aggregated with sized magnetite in the absence of aggregating reagents, high shear rates or an external magnetic field. The formation of aggregates is attributed to the presence of the remanent magnetisation in these oxide iron minerals, aminly in the magnetite.