Bridging the gaps: bole and Terra Sigillata as artefacts, as simples and as antibacterial claysBridging the gaps: bole and Terra Sigillata as artefacts, as simples and as antibacterial clays Peer-Reviewed Journal Publication Δημοσίευση σε Περιοδικό με Κριτές 2021-09-032020enMedicinal earths are an important and yet, so far, little scientifically explored archaeological resource. They are almost always identified by their source locality. Our work over the last few years has focused on their chemical and mineralogical characterization and their testing as anti-bacterials. This paper presents the results of the mineralogical analysis and antibacterial testing of six medicinal earths, bole or Terra Sigillata (stamped earth) of unknown date and provenance in the Pharmacy Museum of the University of Basel. Only one of them, a red (Armenian?) ‘bole’, was found to be antibacterial against both Gram-positive and Gram-negative bacteria. A yellow powder of Terra Tripolitania was mildly antibacterial and against one pathogen only. We argue that medicinal earths are in a pivotal place to bridge the gap between currently dispersed pieces of information. This information relates to: (a) their nature, attributes, and applications as described in the texts of different periods, (b) the source of their clays and how best to locate them in the field today, and (c) the methods employed for their beneficiation, if known. We propose that work should be focused primarily onto those medicinal earths whose clay sources can be re-discovered, sampled and assessed. From then on, a parallel investigation should be initiated involving both earths and their natural clays (mineralogy at bulk and nano-sized levels, bio-geochemistry, microbiological testing). We argue that the combined study can shed light into the parameters driving antibacterial action in clays and assist in the elucidation of the mechanisms involved. http://creativecommons.org/licenses/by/4.0/Minerals104Venieri_et_al_Minerals_10(4)_2020.pdfChania [Greece]Library of TUC2021-09-03application/pdf719.7 kBfree Venieri Danai Βενιερη Δαναη Gounaki Iosifina Γουνακη Ιωσηφινα Christidis Georgios Χρηστιδης Γεωργιος Knapp Charles W. Bouras-Vallianatos‏, Petros‏ Photos-Jones, Effie MDPI Armenian bole Terra Sigillata Antibacterial clays Lemnian Earth Terra Tripolitania Medicinal earths