A bronze sword unearthed from the Terracotta Army pits was found to carry a chromium salt oxide layer, keeping it rust-free for over two thousand years. The same technology was patented by Germany in 1937 and the United States in 1950. Probes of the Qin mausoleum also found mercury anomalies in the burial mound, tens of times higher than surrounding soil, matching the Records of the Grand Historian account of rivers and seas formed from mercury.
Account
A bronze sword unearthed from the Terracotta Army pits was found to carry a chromium salt oxide layer, keeping it rust-free for over two thousand years. The same technology was patented by Germany in 1937 and the United States in 1950. Probes of the Qin mausoleum also found mercury anomalies in the burial mound, tens of times higher than surrounding soil.
Contested
Chinese academic circles disagree on the chromium coating process. Some scholars believe the surface chromium layer may have been natural adsorption from deep soil, not an intentional ancient technique.
Sources
- Terracotta Army archaeological team excavation report
- Records of the Grand Historian