Measurement of anisotropy of magnetic susceptibility: A comparison of the precision of torque and spinner magnetometer systems for basaltic specimens

Five replicate measurements of the low-field anisotropy of magnetic susceptibility (AMS) of 10 basaltic samples were made using a torque magnetometer and a Digico spinner magnetometer to compare the azimuthal precision for these instruments. AMS measurements of 100 additional basaltic samples are used to compare magnitude determinations between the two devices. It is shown that although analyses using the torque magnetometer are more time consuming that similar measurements using the Digico spinner magnetometer (1.5 h as opposed to less than 4 min), the precision of the torque magnetometer is superior. The instruments gave similar results for measurements on two samples constructed from homogeneous dispersions of equidimensional magnetite grains.