According to literary sources, the various products of vulcanicity were in great demand for both manufacturing and medicinal purposes in the ancient world, as they are today. These include pumice, fuller's earth (a form of calcium montmorillonite), sulphur, and the alumen of the Romans, which was probably aluminium sulphate, or a related substance. The island of Melos, in the Cyclades, was particularly noted in Antiquity for its mineral products, and in this brief article an attempt is made to summarize the references to these products by the various Greek and Roman authors, and to identify them and the people concerned with their mining and extraction in Antiquity, on the basis of recent geological and archaeological observations made by the author on the island.