In the last decades, the discipline of medical geology has developed, elucidating further the connection between medicine and the environment. The association between geological materials, i.e. minerals and rocks, has ancient origins. It is known, by the study of the ancient sources, that the systematic approach to geology began in Ancient Greece. The most important Ancient Greek source is the work of Theophrastus «On Stones», which was written between the 4th and the 3rd centuries BC. Even in cultures with less developed knowledge of geology per se, many rocks and minerals were regarded as having healing or even prophylactic properties, i.e. they were able to repel diseases. Ancient Greek Medicine as systematised by Hippocrates and Galen, included rocks and minerals as medicines and cures. In fact, Galen was amongst the first to realise that there were considerable differences in the properties of curative geological materials, depending upon the method of extraction and the processing stages He seems to have visited both Cyprus and Lemnos, which were regarded as the medicinal centres of Antiquity. The extraction, processing and use of minerals were quite developed in Ancient Greece, and their medicinal use was only one amongst numerous different ones. From the ancient times, since the present day, the majority of mineral-related therapies, are clay-related, meaning that their principal therapeutic components are clay minerals. Most such therapies are external, and are focusing on skin pathologies, or have a cosmetic purpose. However, there are many documented cases of geophagy, where edible clays are consumed, either as dietary supplements or as therapies. The external use of clay, called pelotherapy, and aside from its cosmetic and skin-healing applications, recent research indicates that it might be used also as a remedy for rheumatoid arthritis. Finally, psammotherapy uses sand baths in special soils, to treat muscular and/or skeletal diseases, since marine sand can tonify the muscular system. Also associated with the geology of an area is thermal medicine, which comprises all those practises associated with thermal treatments, and is believed to have originate in Ancient Greece.
Regarding examples of medicinal earths used in Ancient Greece, which have been studied using modern methods, the red pigment, called miltos, which existed in two variations – regarding medicine – Lemnian earth and Kean earth; the Samian earth and the solfataric alum of Melos have to be mentioned. Miltos has a strong antiseptic potential against bacteria, although this does not apply to all the studied samples to date. Samian earth, whose main component is believed to have originated from the borate deposits of the island has proven that indeed Samian earth possesses antimicrobial properties. Finally, stypteria lithos has astringent properties, leading to the shrinkage of mucous membranes, and it is for this reason that it was used as a haemostatic agent. In addition, modern research has demonstrated that alum has strong antibacterial properties. Through the ages, in most cultures, the association between health and the environment was evident, and health was perceived as some kind of balance between the human body, as an integral part of the cosmos, and the natural environment .
It is only natural that the earth, and its primary constituents, minerals and rocks, are associated with health and well-being. Although relevant recent is still in its infancy, hopefully, within the next decade we will have a more complete understanding of these ancient medical geology practises, and their potential adaptation for use in modern medical and traditional medical practises.