A ground magnetic survey of a portion of the Montagne du Sorcier showed an off-scale positive anomaly (>12,000 gamma ) over a magnetite-bearing serpentinite and an 11,000-gamma negative anomaly immediately south of it. Measurement of the magnetic properties of specimens from 73 oriented cores from the serpentinite indicate that the direction of remanent magnetization is that of the present Earth's field and therefore in the same direction as the induced magnetization. This suggests that the unusual shape of the anomaly can be explained by the topography of the mountain. The alinement of the remanent magnetization with the present Earth's field may be due to viscous realinement of the remanent magnetization. The sill is a possible source of iron ore.