RESUMO
Crystal defects and chemical reactions occurring at scales beyond the resolution of light microscopes have major effects on the chemical and physical properties of rocks and minerals. High-resolution imaging, diffraction, and chemical analysis in the transmission electron microscope have become important methods for exploring mineral defect structures and reaction mechanisms and for studying the distribution of phases resulting from reactions. These techniques have shown that structural disorder is common in some rock-forming minerals but rare in others. They have also established mechanisms by which many reactions occur at the atomic cluster scale. These data thus provide an atomistic basis for understanding the kinetics of geological reactions. Furthermore, apparent major-element, minor-element, and trace-element chemistry of minerals can be influenced by submicroscopic inclusions or intergrowths, which commonly form as products of solid-state reactions.
