A Preliminary Study On the Electrical Signatures of Some Iron and Stony Meteorites and Their Dependence On Nickel Content

Abstract

The present study is considered as an exploratory study of electrical properties of meteorites at variable current frequencies, called the electrical signature. The electric resistivity has been measured at different frequencies, varying between 1 and 100 KHz for some iron meteorites (Mundrabilla and Gibeon meteorites), stony meteorite samples (NWA 869, NWA 7629 and Ghubara) and Fe-Ni alloys, of known Ni concentration, which have been prepared and used as standards to be compared with the studied meteorites. In addition, SEM studies supported by EDX technique have been applied. The SEM and EDX displays enabled us to obtain the chemical composition and internal structural fabrics of the studied samples. Porosity and density (bulk and grain densities) have also been measured for both types of meteorites. Porosity values of the studied meteorites are very low (∅ ≤ 3%) and correspond to micro vugs and cracks. The grain density of non-weathered samples varies from 3.48 g/cm3 for the stony meteorites to 7.91 g/cm3 for the iron meteorites. The obtained electrical signatures are diagnostic for each type and can be used to detect quantitatively the concentration of Ni. The electrical signature of stony meteorites is much simpler than that of iron meteorites, and simpler signatures have been obtained at higher Ni concentrations.