CHEMICAL AND MINERAL CHARACTERIZATION OF GRAY SEDIMENTS USED TO MODEL CHINCHORRO BODIES

This paper presents the chemical and mineralogical characterization of inorganic gray sediments used by the Chinchorro people to make their black mummies or reconstructed bodies. Thirteen samples token from an inner layer of the black mummies (ca 4,000-2,800 BC) were studied to determine its mineralogical composition, plastic quality and whether it contained clay. The samples were analyzed at the Laboratorio de Investigaciones Medioambientales de Zonas Aridas, LIMZA (CIHDE-Universidad de Tarapaca), using energy dispersive X-my fluorescence (EDXRF) and at the Laboratorio de Ciencias Geologicas de la Universidad del Norte, using X-ray diffraction and scanning electronic microscopy. In addition, experimental ceramic tests were undertaken at the Laboratorio de Conservacion del Museo Arqueologico de la Universidad de Tarapaca, Arica. EDXRF result indicates the gray material was composed primarily of SiO2(68%), Al2O3(13%), Fe2O3 (7%) and to a lesser extent, K2O (4%), CaO (3%), Cl (2%), SO3 (1%), and TiO2( 1%). DRX analysis shows the mineralogical composition is quartz (30%), albite (26%), sanidine (15%) and muscovite (12%) among others. These results, along with the experimental ceramological testing and microscopy analyses, suggest that Chinchorro morticians used natural sediments that can be considered as medium to high quality clays to prepare the black mummies and did not add ground shells or grasses to the mixture.