Degradazione di un inchiostro metallico in un manoscritto del IX secolo

An anomalous metallic ink was identified on an ancient Italian manuscript datable to the 9th century, known as Homilies on the Gospels by Gregory the Great and belonging to the Archives and Chapter Library of Vercelli. Many lines of text and several decorated initials in this manuscript at present are green in colour, but descriptions of this manuscript mention letters decorated in gold. It is possible to hypothesise that the ink had originally been gold in appearance and then, due to a degradation phenomenon, that this colour had changed to green. In situ analyses carried out on the manuscript using Raman and XRF spectrometry made it possible to clarify the original composition and the nature of the alteration process on the ink. It was found to be a copper-zinc alloy in which the copper had turned into carboxylate, possibly due to exposure to volatile compounds generated by the wood of the cupboards in which the manuscript was kept.