Vitreous tesserae from the calidarium mosaics of the Villa dei Quintili, Rome. Chemical composition and production technology

In the 29 tesserae studied in this research, the colors of glass were strictly correlated to the concentrations of coloring agents, the two main coloring ions identified were copper, introduced in the majority of samples as bronze scrap, and cobalt. Finally, the levels of trace elements indicate the use of mature sand, rich in quartz and poor in heavy metals and clay minerals, for the production of all samples.