Mineralization in Archaeological Skin: An Interdisciplinary Approach to Conservation Processes and Contextual Relations
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Fig. 1. Pre-Columbian burial at El Gallo Cave.
Fig.2. Localization of El Gallo Cave, Morelos.
these environmental conditions, the calcic-magnesion soils, like the Rendzines, are dominant. The climate is subhumid (warm) with a marked drought period and poor thermal oscillation. The annual average precipitation is 774 mm, and the annual average temperature is 24.1°Celsius. According to the method proposed by C.W. Thomwaite [3] and modified by USDA [4], we estimated that the soil climate corresponds to an ustic regime and an iso-hiperthermic temperature soil regime. In addition there is a fluctuating regime of humidity to drought throughout the year. The vegetation is subtropical dry forest dominated by arborescent species[5]. El Gallo Cave is located NW of Ticuman, in theTlaltizapan municipality, state of Morelos. It is on parallel 18045' N and meridian 9907' W (Fig.2), with an altitude of 1200 m. This cave is structurally formed by the dissolution of limestone which has created a system of caverns. Access is by a 75 m tunnel, descending 35 m to chamber 1. Here the studied materials were found. The microenvironmental conditions are stable, with an average temperature of 2 0 °Celsius and a relative humidity of 45%. METHODOLOGICAL DESIGN The determination of the stratified minerals on the canine skin were identified by three main stages: Stage 1. Obtaining Samples. Skin samples (epidermis and dermis), with an area of 0.5 cm2 , were obtained from the dog avoiding contamination. The material was dried and analyzed (pressure/humidity of 1500 kPa). The samples corresponded to two tissue types: thin tissues (epidermis with poorly limited constitutive layers) and thick tissues (epidermis and dermis)[6]. Stage 2: Preparing Samples. Samples were prepared for electronical microscopy. They were attached to metallic cylinders and covered with a gold layer by means of vacuum ionization. Stage 3. Analyzing Samples. The analysis involved the following phases: 1. Electronical Microscopic Observation. Samples were studied in the Geochemical Laboratory at the Geological Institute of the National Autonomous University of Mexico (UNAM), using a Jeol JSM-35C microscope.
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Both surfaces (external and internal) of the skin samples with the mineral deposits were observed. In addition, the cross-sections (superposition or layer stratigraphy), were magnified between 300 and 6500 X. 2. Microphotography register. The microphotography register was made at the same time as the sample observation and microanalysis by using photographic equipment integrated in the microscope. Negative black and white film was used (Kodak, Verichrome pan VP 120). 3. Microanalysis of X-ray dispersion. A detailed analysis of elements on the inspected sample areas, was made under operational conditions of 15 kV acceleration voltage and 60 seconds of acquisition time. The elements were determined as total oxide forms. RESULTS AND DISCUSSION It is axiomatic that after death, any organic body is destroyed in a short period of time because of the combined action of
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