Laser ablation inductively coupled plasma mass spectrometry analysis of Chinese lead-barium glass: combining multivariate kernel density estimation and maximum mean discrepancy to reinterpret the raw glass used for producing lead-barium glass

Lead-barium glass, which appeared during the Mid-Late Warring States period (475–221 BC) in China, is considered to be a purely Chinese invention due to the unique presence of high barium. However, lead-barium glass was rarely referred to in contemporary Chinese literature and disappeared after the Han Dynasty (202 BC–AD 220). In this paper, 49 samples excavated from five provinces in China have been analysed by LA-ICP-MS for trace element composition. We offer a piece of code to perform multivariate kernel density estimation on four variables in a tetrahedron plot, and then we used maximum mean discrepancy and hypothesis testing for cluster analysis. The results suggest that lead-barium glass was a secondary product made by mixing Chinese lead and barium minerals with imported natron glass, and the Syro-Palestinian coast was the possible source region for the raw glass used to produce lead-barium glass.