Multiscale and Correlative Analytical Electron Microscopy of Extraterrestrial Minerals

This paper presents a unique correlative microscopic method for the structuralcharacterization of extraterrestrial minerals. A fragment from the pallasite Seymchanmeteorite that consists of olivine grains mixed into a metallic iron matrix with variablenickel content was studied from mm-down to nm-size by using the Raman Imaging andScanning Electron Microscopy and analytical scanning transmission electron microscopy.Hyperspectral fast acquisition for energy-dispersive X-ray spectroscopy mapping of acouple of mm2 large area correlated with additional hyperspectral Raman analysis ofsmaller regions in the same area on one hand, and hyperspectral analytic STEMinvestigations at the atomic resolution, on the other hand, provided valuableinformation about the chemical composition, bonding, and crystallography. Theanalysis revealed particles of troilite, schreibersite, and forsterite but also regions ofmixed iron oxides, carbonates, and amorphous carbon as well as plessite regions withnanometre-sized taenite needles dispersed in the kamacite matrix.