The evidence presented in this paper is a first effort to contextualize aspects related to the sourcing, production and uses of red paint during the second millennium BC in Northern Peru. The site tested was Gramalote, a fishing settlement of the Peruvian North Coast. The results show that the inhabitants of this settlement had access to a local source of hematite but they also used cinnabar that came from a distant region located in the southern highlands. Based on the abundance of lithic and bone tools, shell containers and ceramic seal stamps, the authors of this article study the process behind the production of this painting. Using physicochemical techniques such as Portable X-ray fluorescence (XRF) technology complemented with structural analysis through X-ray diffraction, applying conventional and synchrotron radiation on selected samples, the authors look at issues related to sourcing, production and uses of the red pigment. In addition, isotopic analysis helped to determine the provenience of cinnabar which is also the earliest evidence of human use of this mineral in the Andean region. Temporal and contextual distribution of these artifacts is analyzed to understand the manipulation and uses of the red paint. Finally, this study also gives a glimpse of the symbolic meaning red pigment could have played in the daily life of a second millennium BC maritime community on the Pacific coast of Peru.
Tambo Colorado is one of the most impressive archaeological sites in the Southern Peruvian coast, because of its stunning architecture, its extraordinary pictorial decoration, and its strategic location in the section of the Great Inca Road. The Research Project Tambo Colorado considers necessary to conduct a comprehensive analysis encompassing nature of the materials (archaeometric analysis) as well as a proper understanding of their conservation status of its architecture. In this regard interdisciplinary research provides the necessary tools to achieve these goals. For this reason our team is integrated by archaeometrists, engineers, conservators and archaeologists. Due to of this transdisciplinary approach, one of the main objective is the study of painting technology developed by the craftsmen of the site. The first results obtained, thanks to an analytical strategy combining observation and elemental and structural analysis (colorimetry, SEM-EDS, XRF, XRD and SXRD), allow us to identify the coloring materials used. These data enabled to reconstruct the operational chain followed to elaborate the murals (since the pigments extraction to the making of the murals) but also to consider and develop a suitable surfaces conservation plan.
RESUMENResultados de medidas de difracción de rayos-X mostraron una secuencia de modificaciones químicas y estructurales como la deshidratación, descomposición y formación de nuevas fases en arcillas sometidas a aumentos graduales de temperatura. Los componentes de las muestras fueron determinados, identificándose montmorillonita-Ca, vermiculita, muscovita, caolinita, chlorita, illita, cuarzo y albita. El refinamiento estructural por el método de Rietveld reportó, en todas las muestras, mayor porcentaje de arcilla noexpansiva en comparación con la expansiva. A 250°C, la montmorillonita-Ca presentó una disminución drástica en su distancia interlaminar, de 1.5 nm a 1.0 nm, debido a la remoción del agua superficial y de los poros, así como de la contenida en la región interlaminar. Para el caso de la vermiculita, esta disminución es mucho menor (~0.04 nm), en tanto que la caolinita no presenta disminución significativa de este parámetro. La vermiculita estructuralmente colapsa a ~350°C, en tanto que la caolinita lo hace a ~500°C, mientras que nuevas fases aparecen, como la ortoclasa y anorthita. Palabras llave: arcilla, difracción de rayos-X, método de Rietveld. ABSTRACTResults of measures of X-ray diffraction showed a sequence of chemical and structural changes such as dehydration, decomposition and formation of new phases in clays subjected to gradual increases in temperature. The components of the samples were determined identifying Ca-montmorillonite, vermiculite, muscovite, kaolinite, chlorita, illite, quartz and albite. The structural refinement by the Rietveld method reported the presence of a higher percentage of non-expansive clay compared to the expansive in all samples. At 250°C, Ca-montmorillonite presents a drastic decrease in its interlayer distance, from 1.5 nm to 1.0 nm, due to removal of water from the surface and pores, as well as of water contained in the interlayer region. In the case of vermiculite, this decrease is much smaller (~0.04 nm), while kaolinite does not present significant decrease in this parameter. Vermiculite structurally collapses to ~350° C, whereas kaolinite makes it to ~500° C, while new phases appear, such as orthoclase and anorthite.
RESUMEN A pesar de la excepcional arquitectura y policromía del sitio arqueológico de Tambo Colorado, no ha habido trabajos de conservación ni en las estructuras arquitectónicas de tierra cruda, ni en las superficies. Estos trabajos requieren una comprensión adecuada del estado de conservación de la arquitectura del sitio y el análisis de los materiales utilizados. Con este propósito, los resultados del presente estudio pretenden explicar la naturaleza de los materiales (pigmentos) utilizados en las pinturas murales, así como determinar las fuentes de estos materiales (canteras). Para ello, pigmentos de cantera fueron investigados por la técnica de difracción de rayos X, usando radiación sincrotrón, y refinamiento estructural por el método de Rietveld. Se determinó la composición de los pigmentos, identificando las fases de anortita, hematita, cuarzo, clorita, halita, yeso, ortoclasa, illita, jarosita, calcita, caolinita, zinwaldita, cristobalita, anhidrita y albita. El refinamiento Rietveld confirmó la presencia de estas fases y determinó el porcentaje en peso de cada una de ellas.
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