This study provides new rock magnetic and magneto-mineralogical data including Mossbauer spectroscopy of basaltic drill cores from the Stardalur volcanic complex, Iceland, in order to better understand the strong magnetic anomaly, which is caused by an extraordinary high natural remanent magnetization (NRM). NRM and magnetic susceptibility (X) display a positive linear correlation (R(2) = 0.81) and reach very high values up to 121 A/m and 148 x 10(-3) SI. Although a Curie temperature of 580 degrees C and a Verwey transition at about -160 degrees C is indicative of magnetite, (X)-T heating experiments in argon and air atmosphere and thermal demagnetization measurements of NRM revealed a slight cation-deficiency. According to induced remanent magnetization experiments the remanence is carried solely by this low coercive phase. Minor titanomaghemite with a T