Cathodoluminescence (CL) microanalysis provides high-sensitivity spectra and high-resolution images associated with impurity and structural defects at the nanoscale and from luminescent materials including minerals, semiconductor, and dielectric/insulating materials. Cathodoluminescence is the non-incandescent emission of light (photons) emitted from materials excited by an electron beam. CL photons (UV-VIS-NIR) are produced as a result of electronic transitions between the conduction and valence band and may also involve electronic transitions associated with defect levels within the band gap. Microscopic defects such as imperfections and impurities influence the optical, electrical, and mechanical properties of scientifically and technologically important materials. CL microanalysis is therefore a useful microanalytical technique for characterizing these properties with high sensitivity and spatial resolution. CL image resolution can range from sub-10 nm to microns, dependent on experimental arrangement (STEM-CL, SEM-CL, optical CL microscopy), electron beam parameters, specimen configuration, carrier diffusion, etc. The sensitivity of CL microanalysis is dependent on the specimen and, in the absence of self-absorption and competitive recombination centers, can be several magnitudes more sensitive than X-ray microanalysis. In particular, quantitative CL microanalysis of trace impurity concentrations while challenging has recently been shown to be possible for a range of minerals.