In most archaeological researches, ceramic cathodoluminescence images are conventionally exploited in a descriptive way (paste colour, inclusions). In this study, a new approach was employed: image's RGB histograms were used in order to differentiate several ceramics recently discovered at the archaeological site of San José de Moro located in northern Peru. Cathodoluminescence coupled with chemometric methods appears as a good method to characterize and particularly to produce a systematic classification of complex materials such as archaeological ceramics. Our results were compared with the archaeological and classical background knowledge and this allowed confirming that Mochica Fine Line and Mochica Polychrome were the most similar archaeological groups, at Mochica times, because of the use of the same raw material for production. However, Highland Cajamarca is the most different ceramic group from the other studied ones due to the use of different raw materials from Cajamarca valley located 100 km east of San José de Moro site.

Abstract:The famous archaeological site of San José de Moro (SJM) located in the Jequetepeque Valley (JV) represents one of the best-preserved pre-Columbian Mochica cemeteries uncovered along the north coast of Peru. SJM was a regional ritual centre where elites and the general population of all JV met to celebrate ceremonial events. Its role as a place of regional integration and coordination continued long after the disappearance of the Mochica and SJM was continuously occupied throughout the Late Mochica Period (8th-9th c. AD) and into the Transitional Period (9th-10th c. AD). Even though the abandonment of Mochica traditions in SJM (funerary practices and ceramic styles) appears quite rapid, SJM was constantly occupied whereby local traditions were being reshaped. During this time various styles of ritual ceramics from different traditions (Mochica, Cajamarca and Wari) were buried within ceremonial and funerary contexts. This research involves archaeometric studies of excavated painted diagnostic ceramic sherds representing four distinctive pre-Columbian typologies present at this site-Mochica fineline bichrome, Mochica fineline polychrome, coastal Cajamarca and Highland Cajamarca ceramics. For this study handheld portable X-ray fluorescence spectrometer (HHpXRF) instrumentation was operated in situ in order to (1) perform non-destructive trace element analysis (2) to assess if Cajamarca ceramics were further elaborated using the same raw materials employed by the Mochica potters of SJM, and (3) to establish whether or not Mochica and Cajamarca ceramics were truly technological markers in the lower part of the Jequetepeque valley.

The potential of chemical information obtained by scanning electron microscopy (SEM) based methods is examined for archaeometric studies on polychrome decorations of ceramics. Achieved on polished block sections, the feasibility and benefits are demonstrated as case studies using pre‐Columbian pottery (Wari, Moche, and Cajamarca). Elemental mapping and profiling by X‐ray spectroscopy (EDS) allow separate consideration of the paste in the body, slip, binder and pigments in the polychrome decoration. Compositional profiles across decorative layers substantiate the use of manganese ores for the formation of jacobsite as black pigment. To enlighten trade relations, technological transfer and shared heritage of pre‐Columbian cultures in Peru, the results provide information about local or non‐local pottery production.

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