Crucibles and moulds from Los Nogales: Technological study of technical ceramics from the Late Period in the Aconcagua Valley, Central Chile

The spread of the Tawantinsuyu in the Aconcagua Valley (Central Chile) is thought to have been culturally mediated, avoiding military coercion, and thus leading to different forms of cultural acceptance, resistance or hybridisation. However, very few studies have discussed how this process is reflected in the metallurgical production during the Late Period (ca. AD 14001530). The result of a technological study on a group of crucibles and moulds from Los Nogales (Aconcagua valley), using optical microscopy, petrography, SEM-EDS, XRD and FTIR is presented here. Results indicate that the raw materials used were local igneous rocks obtained from alluvial deposits, mixed with small amounts of smectite-montmorillonite clay. Moulds also contained bone ash as temper. Firing temperatures were estimated between 800-850 degrees C for moulds and above 900 degrees C for crucibles. Their manufacture technology and morphology indicate that these technical ceramics were made following a technological tradition originated in northwest Argentina that was introduced to the Aconcagua valley during the expansion of the Tawantinsuyu, and accepted by local communities.