Analysis of Geological Ochre: Its Geochemistry, Use, and Exchange
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Open Journal of Archaeometry 2013; volume 1:e15 Analysis of geological ochre: ture scientists (Figure 1) all encounter collec- tion materials made using iron oxides. Correspondence: Anne Kingery-Schwartz, its geochemistry, use, and Moreover, while the fields of those interested Kingery Conservation LCC, 516 A Street NE, 104 exchange in the US Northern in museum collections are diverse, the ability Washington DC 20002, USA. Great Plains to characterise iron oxides precisely offers Tel./Fax: +1.202.355.8664. answers to many of these individuals – such as E-mail: [email protected] Anne Kingery-Schwartz,1 the geological history of a place or information Key words: ochre, INAA, XRF, XRD, Northern Rachel S. Popelka-Filcoff,2 about a culture that settled in a particular time Great Plains. and place. However, fully characterizing these David A. Lopez,3 Fabien Pottier,4 iron oxides is difficult as they are complex het- Citation: Kingery A, Popelka-Filcoff RS, Lopez DA, Patrick Hill,5 Michael Glascock6 erogeneous mixtures of minerals. This study Hill P, Glascock M, 2013. Analysis of geological 1Kingery Conservation LLC, Washington, aims to investigate various analytical tech- ochre: its geochemistry, use, and exchange in the DC, USA; 2School of Chemical and niques that have the potential to characterise US Northern Great Plains. In: RH Tykot (ed.), Proceedings of the 38th International Symposium Physical Sciences, Flinders University, them. on Archaeometry – May 10th-14th 2010, Tampa, Adelaide, South Australia 5001, Florida. Open Journal of Archaeometry 1:e15 Australia; 3Independent Geological Ochre in museum collections Consultant, Billings, MT, USA; 4Centre de including the National Museum of Acknowledgments: the University of Missouri Recherche sur la Conservation des Research Reactor Facility (MURR) Archaeometry the American Indian Lab and staff. National Science Foundation Collections, Museum National d'Histoire Today, many museums house painted raw- (#0802757): Michael D. Glascock, P.I. The Andrew 5 Naturelle, Paris, France; Little Big Horn or semi-tanned hide objects – robes, shirts, W. Mellon Foundation: Marian Kaminitz, Jessica College, Crow Agency, MT; 6University of shields, leggings, moccasins, etc. Pigments Johnson, Susan Heald, Emily Kaplan. National Missouri Research Reactor Facility, that were either mined from the earth or trad- Museum of American Indian: Jeff Speakman, Rae Columbia, MO, USA ed are applied to the substrate using water, Beaubien, and Lynn Brostoff. Smithsonian Museum Conservation Institute: Tim McCleary. cactus juice, or hide glue as binders (Ewers, Little Bighorn College: Putt Thompson. Little 1939; Moffat et al., 1997; Voget, 2001). In par- Bighorn Trading Post: Jack Bailey, rancher in ticular, red ochre (iron oxide) and other red Montana. Abstract pigments, both natural and synthetic, were Samples of pigments indigenous to the US highly prized by prehistoric and historic Native Presented at the 38th International Symposium on th th Northern Great Plains were collected in associ- American cultures (Ewers, 1939; Moffat et al., Archaeometry – May 10 -14 2010, Tampa, Florida. ation with the conservation of a buffalo hide 1997; Blakeslee, 1976; Brasser, 1982; Bunzel, 1932; Danziger and Hanson, 1979; Fewkes, tanned and painted by a Crow Indian(s) in the This work is licensed under a Creative Commons 19th century, which is now in the collection of 1904; Leechman, 1932; Mails, 1996; Mallery, Attribution 3.0 License (by-nc 3.0). the National Museum of American Indian. The 1886; Morrow, 1975; Vestal, 1952; Wallace, pigments were characterised using a series of 1934; Wissler, 1910). In addition to written ©Copyright A. Kingery-Schwartz et al., 2013 analytical techniques – some common and oth- sources, evidence of pigment use remains on Licensee PAGEPress, Italy ers uncommon to the conservation science the objects themselves. Geological studies sug- Open Journal of Archaeometry 2013; 1:e15 doi:10.4081/arc.2013.e15 field, including portable X-ray fluorescence gest ochre was readily available in geographi- (pXRF), X-ray diffraction (XRD), and instru- cally diverse locations, however, there is also mental neutron activation analysis (INAA). evidence that pigments were part of a complex XRF is not capable of differentiating between intertribal trade network that pre-dates contact Institute, reviewed the historical literature and various ochre samples due to high detection with Europeans (Blakeslee, 1976). compared the information of results from limits. XRD can detect some matrix minerals Pigments in the Northern Great Plains gen- portable X-ray fluorescence (pXRF), X-ray dif- in each sample, but these data cannot charac- erally fall into two categories: Anglo trade pig- fraction (XRD), and Fourier transform infrared terise pigments by original source location. ments and indigenously produced pigments. spectroscopy analyses (Miller, 1986). This INAA is capable of characterizing ochres from However, further research into indigenous pig- study provides a good timeline regarding the different sources based on trace element geo- ments suggests some came from intertribal introduction of trade pigments. However, this chemistry; however, the large sample size it trade rather than local mining and production study did not characterise the iron oxide based requires (approximately 100 mg), makes sam- (Blakeslee, 1976). Therefore, the source of pigments in any specific way. Thus no conclu- pling from objects challenging and therefore iron oxide pigments and their similarities to sions could be drawn about the origin of these makes it difficult to use for technical art histo- similarly colored pigments would give insight pigments. Were they trade pigments, were they ry studies that focus on museum objects. INAA into the materials used to decorate these locally mined by the tribes of the Great Plains, is useful if applied to reference materials, such objects and the relation of the objects to each or were they traded from non-local tribes? as historic pigments or known sources for his- other. toric artistic materials. Studies of ochre within the art con- servation field Materials and Methods While many analytical studies within the Introduction conservation field have been conducted on pig- Building up a reference library of deposits of ments, only a few have focused on pigments iron oxide pigments that might possibly have The study of iron oxide pigments has inter- used by indigenous cultures of the Americas been mined by native artists across the conti- ested scholars from a range of material culture and even fewer are specific to the Great Plains nent would illuminate the use and history of fields. Diverse scholars such as geologists, of North America. The one significant study, the pigments used on historic objects made on archaeologists, historians, and material cul- conducted by the Canadian Conservation the Great Plains. Chemical characterization of [page 72] [Open Journal of Archaeometry 2013; volume 1:e15] Technology & Provenance - Stone, Plaster, Pigments samples from known pigment mining areas maroon, and red mudstones were deposited by will establish a foundation for understanding streams flowing across a coastal plain that bor- Results and Discussion the sources of iron oxide pigments. dered a Cretaceous seaway that extended from Research into various analytical techniques Texas to Alaska. The bright colors of the mud- XRD and pXRF results and discus- was conducted to determine if any held poten- stones in these formations resulted from the sion tial to gain a better understanding of iron oxidizing conditions that existed during depo- Results are summarised in Table 1. pXRF oxide materials used for pigments. For this sition of these terrestrial deposits. A smaller allows the detection of most elements in the study, techniques traditionally used for set of samples were taken from a colourful periodic table with atomic numbers above analysing museum collections were re-exam- deposit that oral history holds is a traditional sodium. In the case of mineral pigments, the ined, and techniques not consistently used by site for contemporary artists to gather pig- elements needed to differentiate sources occur the conservation science field were also con- ments (Deer Medicine Rock samples). Of in the transition elements and higher. sidered. The three techniques compared are those pigments collected by indigenous artists, pXRF, XRD, and instrumental neutron activa- some were collected from a trading post where Therefore, pXRF presents an excellent qualita- tion analysis (INAA). The first two are tech- a Cheyenne artist sold them (Trade Pigment tive technique for identifying pigments with- niques require little or no sample, so they are samples in Table 1). Another set were part of a out taking a sample. In the conservation field, utilised frequently by the conservation science paint kit made by a Crow artist (Lame Deer having to remove even the smallest sample field. In the case of pXRF, the analysis of the samples in Table 1). Each sample was analysed from an object is seen as destructive – even if object can be accomplished by holding the by XRD and INAA. The geological samples were the sample is not destroyed during analysis. instrument within a few millimeters of the analysed with XRF. For all the geological samples analysed with surface of the object; therefore no sample is pXRF, iron was the main element detected. In required. For XRD a sample around 1 mg must Instrumental parameters some cases minor elements such