Solving the chrome-plating mystery of the terra-cotta army

In 1974, a Chinese farmer found fragments of a crushed terra-cotta warrior while digging a well. That find led archaeologists to unearth over 6,000 terra-cotta figures guarding the tomb of Emperor Qin. And all those warriors needed weapons—weapons that have remained remarkably well preserved for over 2,000 years. Previous analysis found layers of chromium oxide on the blades and spears of the warriors, leading many to suggest that ancient Chinese manufacturers used a form of chrome plating to protect the bronze weaponry. New research suggests a different source (Sci. Rep. 2019, DOI: 10.1038/s41598-019-40613-7). Researchers at University College London and the Emperor Qin Shihuang’s Mausoleum Site Museum found that the chromium is mainly located where the metal would have connected to handles, shafts, fittings, and fasteners. Further analysis revealed that the lacquer on those parts was the source of the chromium. The exceptional preservation, the researchers say, is due to the dry alkaline dirt in which the finds were buried.