Abstract Microanalysis can provide rapid, quantitative characterization of mineral systems that complements the field- and core-scale observations traditionally made in ore deposits. We review recent innovations in microanalytical procedures and their application to studies of ore deposits. Case studies are presented examining how microanalysis can provide constraints on macroscopic processes within mineral systems. Synchrotron X-ray fluorescence shows centimetre-scale chemical variations associated with proximity to mineralization in samples from Sunrise Dam Gold Mine, Western Australia. Pseudomorphs of igneous plagioclase and chemically driven recrystallization interpreted from electron backscatter diffraction suggest that the system was dominated by fluid-driven brecciation with very little shearing. Both the fluid chemistry and fluid pressure evolved during a protracted sequence of vein formation and alteration accompanying gold mineralization. A second case study of sulphide mineralogy at the Mt Keith nickel sulphide deposit, Western Australia demonstrates how X-ray computed tomography combined with trace element mapping can constrain the chemistry and dynamics of magmatic systems. Large-scale interaction between silicate and sulphide melts, shown by homogenous palladium enrichment in pentlandite, leads to a large proportion of globular ores with a high nickel content. Increasing use of microanalysis in ore deposit geology is resulting in the constant reassessment of established models for ore genesis though a combination of micro- and macroscale datasets.

Analysis of the structures of minerals is an important part of mineralogical investigations. Mineral assemblies are often formed by micro- or even nanocrystals, and it is most interesting to be able to shed light on the crystallography of individual grains, their structure, crystallinity and other properties. This can be done efficiently by the techniques of transmission electron microscopy. Transmission electron microscopy offers not only an ultimate spatial resolution in the imaging mode, but also the possibility of performing diffraction experiments and structure analysis of very small crystals, as well as a range of spectroscopic techniques revealing chemical composition and other properties of the crystals. This chapter reviews the basic techniques of transimssion electron microscopy and their application in mineralogical crystallography. A special emphasis is put on the methods of structure analysis of nanocrystals. This field has seen a rapid evolution in recent years, and has transformed from a being niche technique to a widely accepted and commonly used method of structure analysis. Its applications in mineralogy are especially rich and attractive.