Materials science insights into Indigenous rock art painters and ochre pigment materiality at Babine Lake, Canada

Pictographs, and the landscape formations they are featured upon, are culturally significant places among Indigenous communities. Here, we present the results of a field survey and compositional analysis of pictographs and the mineral pigments used to produce them at Babine Lake (British Columbia), in the traditional territory claimed by the Lake Babine Nation, the Tl’azt’en Nation, and the Yekooche Nation. The monochrome motifs are produced with iron oxide mineral pigments (red ochre), and are all painted on prominent, open-air rock faces overlooking deep water. This study also includes collection and analysis of red ochre pigment sources within the area for comparison to the pictographs. Using a series of microanalytical methods applied to the local raw materials and rock art paints, we offer insights into characteristics of pigment materiality, such as artistic selection of minerals with different physicochemical properties and the chaîne opératoire of paint preparation. Our results show that rock art painters active at Babine Lake chose a diversity of iron oxide types to produce different pigment mixtures with distinctive properties, including the harvesting and thermal enhancement of iron-rich biominerals from colonies of aquatic, iron-oxide-producing bacteria.