In the legend of Atlantis, orichalcum is a reddish metal, mined in Atlantis but known only by name after the island's disappearance. According to Plato the mineral was found in many parts of Atlantis, being considered second only to gold in value.

The three outer walls of the temple to Poseidon and Cleito were clad respectively with brass, tin, and the third, which encompassed the whole citadel, "flashed with the red light of orichalcum".

Some sources call orichalcum mountain-brass or gold-brass. Perhaps it was copper or a bronze. In Latin it is called aurichalcum; the word is derived from the Greek word ορειχαλκον, which may be transliterated as oreichalkon.


In numismatics, orichalcum is the golden-colored bronze alloy used for the sestertius and dupondius coins. It was considered more valuable than copper, of which the as coin was made.