Tracing literacy in Roman Conimbriga: insights from the metallurgy and ink of a Biebrich inkwell

Abstract

This study presents a comprehensive investigation of a Roman metallic inkwell, identified as a Biebrich type typical of the first half of the 1st century CE, which was unearthed in the ancient town of Conimbriga, Portugal and remarkably preserved residues of its original ink. A multi-analytical methodology was employed to characterise both the alloy used in the inkwell production and the type of ink, integrating elemental techniques (X-ray fluorescence and scanning electron microscopy with energy-dispersive) and spectroscopy with molecular analyses (chromatography, nuclear magnetic resonance, analytical pyrolysis, Fourier-transform infrared spectroscopy, and Raman spectroscopy). The results revealed that the inkwell, which was cast from a bronze alloy consisting of copper, tin and lead, contained ink residues that were primarily composed of amorphous carbon, which was derived from the combustion of organic matter and mixed with beeswax as a binder. Additional components included calcite and phosphate groups consistent with bone black, along with iron, indicative of a mixture with iron-gall ink components. This study identifies a rare example of ‘mixed ink’ at Conimbriga, providing direct archaeological evidence that advances debates on the chronology, diversity, and transmission of ink technologies in the Roman world. This find represents the first documented Biebrich type inkwell discovered on the Iberian Peninsula, significantly expanding the known geographical distribution of this artifact type and offering new insights into Roman writing technologies and trade networks in the western provinces.