Analysis of geological ochre: its geochemistry, use, and exchange in the US Northern Great Plains

Abstract

Samples of pigments indigenous to the US Northern Great Plains were collected in association with the conservation of a buffalo hide tanned and painted by a Crow Indian(s) in the 19th century, which is now in the collection of the National Museum of American Indian. The pigments were characterised using a series of analytical techniques – some common and others uncommon to the conservation science field, including portable X-ray fluorescence (pXRF), X-ray diffraction (XRD), and instrumental neutron activation analysis (INAA). XRF is not capable of differentiating between various ochre samples due to high detection limits. XRD can detect some matrix minerals in each sample, but these data cannot characterise pigments by original source location. INAA is capable of characterizing ochres from different sources based on trace element geochemistry; however, the large sample size it requires (approximately 100 mg), makes sampling from objects challenging and therefore makes it difficult to use for technical art history studies that focus on museum objects. INAA is useful if applied to reference materials, such as historic pigments or known sources for historic artistic materials.

Non-Destructive Multi-Analytical Approach to Study the Pigments of Wall Painting Fragments Reused in Mortars from the Archaeological Site of Pompeii (Italy)

“…The bands at 1586 cm −1 and 1319 cm −1 are most probably also related to the presence of G and D bands of the amorphous carbon, which exhibits a strong shift [45,46]. In the past the use of pure hematite as a mineral pigment to obtain the red color was unlikely; the use of red ochre, where the red color is given by the presence of hematite [47,48], is much more likely; moreover, the Raman spectra of hematite and red ocher are very similar [49,50]. The mineralogical composition of the green fragments (Samples 3 and 4) is quite complex.…”

Data pretreatment and multivariate analyses for ochre sourcing: Application to Leopard Cave (Erongo, Namibia)

“…Although ochre has long been reported in archaeological contexts and rock art pigments have been analyzed since the end of the 19th century (Moissan, 1902(Moissan, , 1903, ochre geochemical fingerprinting only developed during the last two decades thanks to analytical developments (Chalmin & Huntley, 2017). Two approaches can be distinguished within ochre provenance studies, both involving the analyses of archaeological material and geological references: 1) the ana-lyses of elemental composition and more precisely trace elements (David et al, 1993;Green and Watling, 2007;Popelka-Filcoff et al, 2007Eiselt et al, 2011Eiselt et al, , 2019Beck et al, 2012;Montalto et al, 2012;Scadding et al, 2015;Zipkin et al, 2017Zipkin et al, , 2020Lebon et al, 2018;MacDonald et al, 2011MacDonald et al, , 2013MacDonald et al, , 2018Velliky et al, 2019;Pierce et al, 2020); and 2) the analyses of geological, mineralogical and geochemical information (Iriarte et al, 2009;Salomon et al, 2012Salomon et al, , 2014Kingery-Schwartz et al, 2013;Pradeau et al, 2016;Dayet et al, 2016;Cavallo et al, 2017;Lebon et al, 2019).…”

Geochemical and mineralogical fingerprints to distinguish the exploited ferruginous mineralisations of Grotta della Monaca (Calabria, Italy)

“…The elemental, mineralogical or isotopic characterisation of ferruginous mineralisations from geological outcrops and archaeological assemblages has become increasingly common for geoarchaeological interpretations, particularly to support the identification of ancient mining strategies and the construction of resource use-trade-exchange models (e.g., [2,20,24,25,33,55,58,63,81,112,113,116,123,[127][128][129][130]142,148,154]). Even if the cultural implications of the use of ferruginous mineralisations are fairly well documented through the study of raw materials and archaeological artefacts, very little is usually known regarding their systematic procurement, exploitation and processing strategies during prehistory.…”