"TIL In 1965, an excavation team discovered the Sword of Goujian in a tomb in Hubei, China. Encased in a nearly air-tight wooden box next to a skeleton. The sword is over 2500 years old but was in perfect condition, test affirmed that the blade could easily cut a stack of twenty pieces of paper."
from Wikipedia
Amount of elements by percentage
Part examined
Copper Tin Lead Iron Sulfur Arsenic
Blade 80.3 18.8 0.4 0.4 trace trace
Yellow pattern 83.1 15.2 0.8 0.8 trace trace
Dark pattern 73.9 22.8 1.4 1.8 trace trace
Darkest regions 68.2 29.1 0.9 1.2 0.5 trace
Edge 57.3 29.6 8.7 3.4 0.9 trace
Central ridge 41.5 42.6 6.1 3.7 5.9 trace