Chemical analysis of pigments in Brazilian rock art (Piaui)

Abstract

O presente trabalho apresenta uma nova proposta de estudo dos sítios de arte rupestre da região Sudeste do Piauí onde utilizamos técnicas de exame e de análises físico-químicas para fornecer dados sobre a técnica de execução dos grafismos, casos de pinturas retocadas, superposições, técnicas de fabricação dos pigmentos, constituição química dos pigmentos, localização de fontes de matéria-prima, relações existentes entre pinturas rupestres e camadas estratigráficas e estado de conservação das pinturas. Nosso estudo visou sobretudo o conhecimento mais preciso dos pigmentos utilizados nesta arte rupestre, sua composição química, mineralógica e suas relações com o suporte rochoso.

Multi-Analytical Characterization of Rupestrian Precolonial Paintings of Inhuma, Piauí, Brazil

“…However, it was observed that for the sample SE1902 (white pigment), the intensities of analytical signals of this element and of sulfur (S), were much higher than those of the analytical blank (rock support) and other samples under study, indicating that it can be resulting from the raw material, such as gypsum (CaSO 4 •2H 2 O) and/or anhydrite (CaSO 4 ), used in the manufacture of white precolonial paint. 1,10 As a source of gypsum was not found nearby the site, the hypothesis that the rupestrian art was made from pigments based on this mineral and then taken to Ema Site by precolonial painters cannot be discarded, since they maintained a nomadic lifestyle (hunter-gatherers), and the Araripe sedimentary basin, rich in this mineral, is located just over 200 kilometers from the city of Inhuma. 30 Although the literature 1,17,29,31,32 indicates pyrolusite (MnO 2 ) as one of the substances responsible for the black coloration of natural mineral pigments, observed in some rupestrian paintings, this possibility was discarded, due to the absence of an analytical signal for manganese (Mn) in the sample SE1903.…”

“…The State of Piauí, as well as the entire Brazilian Northeast, holds a rich archaeological archive, 1,2 distributed in nearly 100 municipalities, where there are around 2,000 archaeological sites registered on the National Registry of Archaeological Sites (CNSA) from Institute of National Historical and Artistic Heritage (IPHAN). 3 These are mostly rocky formations which served, for thousands of years ago, as shelters for human groups whose permanence was recorded quite expressively through paintings and engravings, and also by other time-persistent remains, such as lithics, ceramics, fires, and human skeletons, among others.…”

“…12 There are several iron chromophores responsible by the ocher color shifting, being the most commons: hematite (α-Fe 2 O 3 ), which has different shades of red, and eventually, the violet (caput mortuum), goethite (α-FeOOH), with a yellowish appearance, limonite (Fe 2 O 3 .H 2 O) from yellow to brown, and black magnetite (Fe 3 O 4 ). 1,[13][14][15] The nuances observed in these colors can be obtained by mixing or heating the pigments. 13 Thus, it is necessary, many times, to use more than one analytical technique to characterize rupestrian pigments, as part of a micro-analysis based approach.…”

“…Finally, there are also white paintings due to the presence of calcite (CaCO 3 ), gypsum (CaSO 4 .2H 2 O) or kaolinite (Al,Mg,Fe) 4 (Si 4 O 10 )(OH) 8 , and black, due to the presence of manganese oxide (MnO 2 ), or animal or wood charcoal. 1,10 In the last decades, the interest in knowing the chemicalmineralogical composition of rupestrian pigments, aiming origin studies, as well as the need to establish intervention parameters for the conservation of these remains, has narrowed the interdisciplinary between archaeology and chemistry. Regarding to the conservation aspects, precolonial rupestrian art, due to its exposition to bad weather, is subject to constant exchange actions with the environment, which cause the appearance of alteration deposits, such as: saline efflorescence, nests of building insects, climbing plants and/or anthropic actions, among others.…”

Marcadores Geoquímicos como Indicadores de Atributos Culturais na Paisagem Geomorfológica no Parque Nacional Serra da Capivara, Piauí-Brasil

“…As cores eram obtidas a partir de ocres ricos em óxidos de ferro (hematita, αFe2O3, e goethita, αFeOOH), carvão vegetal, ossos queimados e óxido de manganês (MnO2), entre outros minerais. É factível também que tenham sido feitas pinturas à base de pigmentos vegetais, que podem ter desaparecido totalmente no decorrer do tempo (Lage, 1996;Guidon, et al 2002;Moraes, 2003;Alves et al, 2011;Cavalcante, 2009). O Parque Nacional Serra da Capivara, além das pinturas rupestres com seus pigmentos, é também reconhecido por seus inúmeros vestígios materiais, como: fragmentos de carvão, instrumentos líticos, sementes, vestígios ósseos humanos e de animais pré-históricos, fragmentos de cerâmica e fogueiras estruturadas, como as que foram evidenciadas no sítio Boqueirão da Pedra Furada, com datações que chegam há pelo menos 50.000 anos, marcas que dizem respeito aos registros mais antigos da presença do homem no continente americano (Parenti, 1993;Felice, 2006).…”