Analysis of a pigment grinding muller from Lacapelle Livron (Tarn and Garonne, France): A tool to prepare cinnabar in a medieval painter workshop or a scriptorium?

A hemispherical stone has been discovered in a 19th century ruined barn at the village of Lacapelle Livron (Tarn and Garonne, France). Its morphology and its mirror polished flat surface showing numerous picketing marks allow to propose a grinding function. Optical microscopic observation shows that numerous striations and de-pressions present on the main flattened surface are resulting from a grinding action on a hard material. Further investigation with SEM-EDS analysis revealed high quantity of cinnabar pigment spreaded on the whole working flat surface and minor traces on other sides, indicating that the stone have been used as a muller to process pigment. Minor incidental traces of orpiment and calcite and an undetermined black organic residue analysed on a smaller flattened side are probably in relation with a second step of pigment processing. Additionally, many vegetal micro-fragments and micro-fibres have been observed in relation with the main working surface and red pigment. Identification of cotton among this fibre material is suggesting a late medieval or renaissance dating. Other observations and analysis put also in evidence iron striated and lined residues on the stone surfaces which could have resulted from the contact metal tool (i.e., knife) used to pick pigment, and from a handle or from the storage in a box. At last, comparison of the artefact can be done with historical pigment mullers from 18th-19th century and representation of painting workshop between the 15th and 17th century can help to propose different possible contexts of usage of this tool.

Automated summary

A hemispherical stone found in a ruined barn in France has been identified as a grinding tool for processing pigments. The stone's polished flat surface shows signs of grinding, and microscopic analysis reveals the presence of cinnabar pigment and traces of other materials. The stone also contains plant fibers and iron residues, indicating its use in pigment processing and contact with metal tools.