Scanning electron microscopy (SEM) in forensic geoscience

This chapter offers an overview of Scanning Electron Microscopy (SEM) and Electron Microanalysis fundamentals using Energy Dispersive Spectroscopy (EDS) and Wavelength Dispersive Spectroscopy (WDS). The main technical features and steps necessary to acquire high-resolution images and obtain reliable chemical analytical results are here briefly summarized. The chapter also describes the main advantages of using this non-destructive technique for forensic geosciences applications, with a particular focus on Automated Mineralogy (AM). This analytical technique expands the potentiality of modern SEM systems, allowing a rapid achievement of mineral classification and modal composition of grain mixtures. Finally, we present real case studies on applying SEM-EDS, WDS, and AM techniques to several fields of forensic geology. Significant examples will include studies on prediction of soil provenance, fingerprinting of the air-borne asbestos, and comparison between soils and sediment samples to test an association between a soil residue found on the crime scene and relevant items for investigation.