Scribes in ancient Rome were using lead ink four centuries earlier than previously thought, according to an analysis of papyri from Herculaneum, a city destroyed, like Pompeii, by the eruption of Mount Vesuvius in A.D. 79. A team of scientists led by Vito Mocella of Italy’s National Research Council for Microelectronics & Microsystems in Naples used micro X-ray fluorescence and diffraction to identify lead in the ink on two documents buried in the eruption (Proc. Natl. Acad. Sci. USA, 2016, DOI: 10.1073/pnas.1519958113). Researchers previously placed the adoption of metallic inks in the A.D. 5th century and believed carbon-based soot ink was the go-to writing medium before that time. This adjustment to the onset of metallic ink use is important because it could improve the interpretation of archaeological artifacts. For example, when archaeologists have found metal residues in pots buried by Vesuvius’s A.D. 79 ash, they’ve assumed the pot held cosmetics but not ink, the authors note. In addition, the team also discovered that a silicon mineral called cristobalite, which forms natural regular lines in the papyrus plant, was used by scribes to keep their writing straight and evenly spaced.