Orichalcum is a metal mentioned in several ancient writings, most notably the story of Atlantis as recounted in the Critias dialogue, recorded by Plato. According to Critias, orichalcum was considered second only to gold in value, and was found and mined in many parts of Atlantis in ancient times. By the time of Critias, however, it was known only by name. In numismatics, orichalcum is the golden-colored bronze alloy used for the sestertius and dupondius coins.
