Assessing manganese mass in adult Chinchorro mummy preparation

Previous studies have investigated where the ancient Chinchorro people of the Atacama Desert obtained the manganese (Mn) used to paint the Black-style mummies. However, a fundamental question remains unresolved: how much Mn was actually required to ornament a Chinchorro mummy? Addressing this problem is essential for understanding the scale of technological investment, mineral procurement, and material scale use involved in this mortuary practice. Here, we present a reproducible workflow that combines geometric body segmentation with minimally destructive materials analysis to generate, to our knowledge, the first per-individual quantitative estimate of Mn use in Chinchorro mummification. Using a nearly complete adult male individual (M1T1C3) as the reference case, supplemented by three comparative individuals, we modeled coating volume from anthropometric data and applied empirical density values obtained from fragment analysis. Measured densities of the Mn coating were 2.07 g cm⁻³ for the facial mask and 2.02 g cm⁻³ for the trunk. Based on these values, we estimated a range of total coating mass of 1668.31 – 2460.85 g for M1T1C3. Thicker Mn coatings produced greater volume and, consequently, higher total Mn mass; variation in thickness largely determines the uncertainty of the final estimate. SmartMap EDS analysis showed local Mn maxima close to 60 wt% and finer, more homogeneous particles in the facial coating. When Mn concentration was incorporated into the mass calculation, the estimated maximum amount of Mn mineral required for this individual was about 1.4 kg. Although these estimates are based on a single individual, the study provides the first quantitative framework for evaluating Mn mass used during mummy preparation in the Archaic period of northern Chile. More broadly, it offers a replicable method for linking body-surface treatment to the scale of mineral extraction and total amount of Mn used. This can be useful for advancing discussions on potential health consequences of using toxic pigments in archaic populations.