pXRF Visits Cornell’s Rare and Manuscript Collections

An early 16th century choirbook from Italy, depicting an illustration of St. Peter and assembled saints.

Portable x-ray fluorescence has found another application in cultural heritage research at Cornell. Over the course of three days in late February, the Landscape and Objects Laboratory’s portable XRF system was used to examine twenty-seven European illuminated manuscript fragments in the Cornell Library Rare and Manuscript Collections. Dr. Louisa Smieska, a postdoctoral researcher at the Cornell High Energy Synchrotron Source (CHESS), collaborated with Ruth Mullett, Medieval Studies graduate student, and Dr. Laurent Ferri, Curator of Pre-1800 Collections, to complete the study.

Ruth Mullett, a PhD student in Medieval Studies at Cornell, aligns the pXRF.

This survey was aimed at identifying the pigments used in the lavishly decorated pages in Cornell’s collection. The team was particularly interested in the blue pigments, and in metallic areas that could be gold. Twenty-three of the manuscripts examined contained copper-based blue pigments, which are probably dominated by the copper-rich mineral azurite. Some of these manuscripts will be examined further at CHESS later this spring to try to determine whether the other trace minerals in azurite blue regions reveal information about the pigment’s provenance. Three manuscripts yielded XRF spectra that could indicate the presence of the precious and costly blue mineral lapis lazuli; these fragments will need to be examined further to confirm this finding. One manuscript contained smalt, a ground cobalt glass, which is an unusual (but not unheard-of) pigment for illuminations.

Ruth Mullett and Louisa Smieska examine the manuscript.

In contrast with the scarcity of costly blue pigments in these manuscript fragments, eighteen of the twenty-one fragments with metallic regions contained gold. Although today gold is considered particularly valuable, the relative cost and rarity of lapis lazuli when these fragments were prepared may have been greater than gold. The survey also identified metallic regions containing tin, which could indicate mosaic gold, a synthetic tin sulfide pigment. The research team is excited to compare this pXRF data with other spectroscopic analyses in the coming months.