-Cr- is a chemical element with atomic number 24. A steely-gray, lustrous, hard metal, chromium takes a high polish and has a high melting point. Chromium is also odorless, tasteless, and malleable. Chromium oxide was used by the Chinese in the Qin dynasty to coat weapons such as bronze crossbow bolts and steel swords found at the Terracotta Army. It came to the attention of the west when it was discovered by Louis Nicolas Vauquelin in the mineral crocoite in 1797.