Hysteresis properties of chondritic meteorites: New results for chondrules from the Allende meteorite

Abstract

Hysteresis properties of twenty individual chondrules from a ~50 cc piece of the Allende carbonaceous chondritic meteorite, with diameters between about 0.08 and 0.44 cm are reported. Coercive force Hc varies from about 3 mT to 32.5 mT. Magnetic remanence to saturation magnetization ratios Mr/Ms vary from about 0.025 to 0.25. If magnetite is the main magnetic mineral, then this variation in hysteresis parameters suggests a range of particle grain sizes and shapes, corresponding to pseudo-single domain PSD and multidomain MD states. No chondrules with single domain SD states were observed. Simple relationships among mass, density, size and shape of chondrules and magnetic hysteresis properties are proposed. Three groups with character- istic coercitivity values are distinguished: (a) group 1 for chondrules with Hc between 0 and 5 mT; (b) group 2 for those with Hc between 5 and 15 mT; and (c) group 3 for those with Hc larger than 15 mT. Group 1 chondrules plot within the MD field, group 2 chondrules plot in the PSD and intermediate fields with low Mr/Ms values, and group 3 chondrules plot in the PSD field with high Mr/Ms values.