Within various types of ore deposits, both syngenetic and epigenetic, elemental or reduced carbon can be observed. Since the recognition of a possible role of organic matter in the formation of Carlin-type and black shale-hosted deposits, the ability to recognize organic residues associated with ore deposits and to identify, interpret, and manipulate the data from these residues are becoming important. Organic geochemical studies are one approach that has become increasingly popular during the past two decades. Organic petrographic studies applied to ore deposits are rare in the literature, but petrographic techniques are more rapid, less costly, and reflected light microscopes are probably more easily available than organic geochemical laboratories. An especially favorable aspect of microscopy is that it offers resolution on a finer scale than organic geochemical techniques, enabling immediate recognition of sample heterogeneity. Historically, organic petrography developed from ore microscopy during the first half of the twentieth century. As a result of the importance of organic petrography in hydrocarbon exploration, several techniques (especially ultraviolet fluorescence microscopy) have been developed which are of potential use to ore microscopists.