An intensive review of the literature as well as microscopic study of many ores shows that gold occurs most frequently in direct contact with the following ore minerals in the order named: pyrite, arsenopyrite, galena, sphalerite, chalcopyrite, bismuth minerals, pyrrhotite, tetrahedrite-tennantite. The most common gangue minerals containing gold are: quartz, carbonates, chlorite, graphite (including other carbonaceous material), and tourmaline. Many other minerals are occasional hosts for gold. Available data suggest that few minerals are effective precipitants of gold under natural conditions although the possibility of precipitation of gold by the host mineral is not denied. Variability in the relation of gold to host minerals is common and it is concluded that each occurrence must be studied separately in deciding which mineral or minerals are valuable guides to gold values.