Orichalcum is a mysterious golden metal that both Mu and Atlantis civilizations both used for their technology. Before orichalcum is fashioned, it's a liquid metal at the room temperature like mercury.
Orichalcum or aurichalcum is a metal mentioned in several ancient writings, including 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. In many sources of pop culture, such as novels and video games, orichalcum is presented as a valuable ore that can be mined and crafted into powerful armor and weapons.