Oricalc, or "Orichalcum," is a legendary 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.\n\nIt is not known for certain what orichalcum was. Orichalcum (or aurichalcum) is generally thought to literally mean "gold copper", but the term derives from the Greek word oreichalkos (from oros, mountain and chalkos, copper or bronze), so more accurately meaning "mountain copper" or "mountain metal". It is alternatively held to be a gold/copper alloy, a copper-tin or copper-zinc brass, or a metal no longer known to man.\n\nIn later years, "orichalcum" was used to describe chalcopyrite or brass. However, these are difficult to reconcile with the text of Critias, because he states that the metal was "only a name" by his time, while brass and chalkopyrite continued to be very important through the time of Plato until today. For that reason, other authors on the subject conclude that orichalcum is either the gold-copper alloy tumbaga, or a metal that is, in the words of Critias, "known only by name today, but was once more than a name."\n\nAn alternative way of understanding the word, "oreichalkos" (or orichalcum), would be to assume that it came from Greek word "orao" (meaning to see or look... to let oneself be seen, appear), "chalkos" (meaning copper... bronzé). Put together they could mean: "seeing-copper", "looking-copper", or "transparent copper". Transparent means "through-appearing" but it is not the transparent thing that "appears": the transparent thing allows another object to be seen through it. Oreichalkos—"seeing copper" or "looking copper"—could be used to fuse to other substances that allowed people to look into objects or through them. It is possible that if energy is passed through it; it could give the desired effect of flashing red.\n\nAccording to Critias, recorded by Plato, the three outer walls of the Temple to Poseidon and Cleito on Atlantis were clad respectively with brass, tin, and the third, which encompassed the whole citadel, "flashed with the red light of orichalcum." The interior walls, pillars and floors of the temple were completely covered in orichalcum, and the roof was variegated with gold, silver, and orichalcum. In the center of the temple stood a pillar of orichalcum, on which the laws of Poseidon and records of the first princes after Poseidon were inscribed. \n\nOrichalcum is also mentioned in the Antiquities of the Jews - Book XI by Josephus, who stated that the vessels in the Temple of Solomon were made of Orichalcum.\n\nThe Golden Plates of Mormonism, although not called orichalcum, were reported by Joseph Smith's brother William to be a mixture of copper and gold, and have "the appearance of gold." The Andean alloy tumbaga fits the same description, being a gold/copper alloy.\n\nIn 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.\n\nMany references originate in Japan but have been translated to English incorrectly. If a translator does not recognize that the reference is to a word in another language and directly romanizes the Japanese instead, errors are likely because of the difficulty of representing the word in Japanese in the first place and the multiple ways it could be romanized.