The earths of the Aegean, the 'industrial minerals' of antiquity, were used daily by people as medicines, pigments, fumigants, mordants or washing powders. Attempting to bring these elusive substances out of the relative obscurity of the documentary sources, this book investigates whether they can be found today on the islands that gave them their names and whether they still 'work'. Probably the most famous of the earths is that from the island of Lemnos in the north Aegean which was bestowed with rituals blessed by pagan gods and the Church for over two thousand years. Having found its source and examined its properties, the authors suggest that ancient myths and rituals may be covert ways of expressing geochemical and/or industrial processes, whose aim was to enhance the properties of a natural material with positive results to health and the prevention of diseases. The need to understand the earths of the Aegean is now very important: they can potentially throw light on a well-recorded practice known as geophagia, the deliberate consumption of clays by humans and animals; equally, they can guide current and ongoing pharmacological research into minerals-based antibiotics. The book includes practical information for the visitor to Lemnos who wants to explore the relevant aspects of the island's history and archaeology.