Superparamagnetic component in the Orgueil meteorite and Mössbauer spectroscopy studies in applied magnetic fields

Abstract

The Orgueil meteorite is a carbonaceous chondrite of group CI. Wdowiak and Agresti1 have recently shown that very small magnetic particles, which exhibit superparamagnetic relaxation below 80 K, are present in this meteorite. They suggested that these small particles consist of magnetite. Using Mossbauer spectroscopy in external magnetic fields we have found that the Orgueil meteorite does not contain superparamagnetic magnetite in any appreciable amount. The meteorite contains another, as yet unidentified iron (III) compound which exhibits superparamagnetic behaviour below 80 K.