A new method of orienting cores is suggested, in which a fluid suspension of magnetic particles is made to solidify and adhere firmly to the formation at the bottom of the well. While the substance is still liquid, the magnetic particles line up in the direction of the earth's magnetic field so that upon solidifying a magnetized body is tightly cemented to the rock. The formation is then cored and the top-most core carrying an inclusion of the polarized material is oriented by means of a magnetometer. When such a core is recovered there can be no doubt as to the fidelity of the result.