а дальше еще интереснее, я вот не уверен что там с добычей хрома и магния для совсем интересных сплавов
Weapons found in burial pits dating from the late 3rd century B.C. Qin Dynasty of the Terracotta Army near Xi'an, China, have been analyzed by archaeologists. Although these weapons were presumably buried more than two millennia ago, the ancient bronze tips of both the swords and crossbow bolts found at the site showed unexpectedly little corrosion, possibly because the bronze was deliberately coated with a thin layer of chromium oxide