Process mineralogical techniques can provide useful information on the mineralogy and textures shown by pyrite and arsenopyrite particles that have been roasted to enhance extraction of gold from refractory gold ores. Dark-field reflected-light microscopy has been found to especially reveal the extent of development of porosity and permeability in the roasted particles. X-ray diffraction has been used to identify the fine-grained, calcium-bearing phases in the roast. Cathodoluminescence microscopy holds promise as a rapid technique for studying the calcium-bearing phases.