The distribution of gallium, germanium, cobalt, chromium, and copper in iron and stony-iron meteorites in relation to nickel content and structure

Abstract

The concentrations of gallium, germanium, cobalt, chromium, and copper have been determined spectrographically in eighty-eight iron meteorites, including representatives from all structural classes, and in nine stony-iron meteorites. The analytical procedures and the structural characteristics of the meteorites studied are described. It is confirmed that concentrations of gallium in iron meteorites are “quantized” but whereas previous workers found three “gallium groups,” four such groups were found in the present work. It has further been found that germanium behaves very much like gallium. Meteorites can be divided into four “germanium groups,” each group corresponding to one of the gallium groups. Compared with gallium and germanium, concentrations of cobalt and copper were found to vary over relatively narrow ranges. Chromium, on the other hand, varies over a range which is fully as great as that observed for gallium. Correlations are observed between the concentrations of cobalt and copper on the one hand, and nickel content and structure on the other, but the relationships are by no means as obvious as they are in the cases of gallium and germanium. The metal phases of all stony-iron meteorites studied are chemically identical in every aspect with the iron meteorites of the largest “gallium-germanium group,” namely that which embraces most of the medium octahedrites and which contains about 15 p.p.m. gallium and 38 p.p.m. germanium.