| Orichalcum | |
|---|---|
 A bronzesestertius coin from the time ofCaligula | |
| Material type | Metal |
Orichalcum (oraurichalcum)/ˌɔːrɪˈkælkəm/ ororichalc/ˌɔːrɪˈkælk/ is a metal mentioned in several ancient writings, including the story ofAtlantis in theCritias ofPlato. Within the dialogue,Critias (460–403 BC) says that orichalcum had been considered second only to gold in value and had been found and mined in many parts of Atlantis in ancient times, but that by Critias's own time, orichalcum was known only by name.[1]
Orichalcum may have been the name for somenoble metal, such asplatinum,[2] as it was supposed to be mined, but has been identified as purecopper or certain alloys ofbronze, and especiallybrass alloys[3] in the case of antique Roman coins, the latter being of "similar appearance to modern brass" according to scientific research.[4]
The name is derived from theGreekὀρείχαλκος,oreikhalkos (fromὄρος,oros, mountain andχαλκός,chalkos, copper), literally meaning "mountain copper".[5]
The Romans transliterated "orichalcum" as "aurichalcum", which was thought to mean literally "gold copper". It is known from the writings ofCicero that the metal which they called orichalcum resembled gold in color but had a much lower value.[6] InVirgil'sAeneid, thebreastplate ofTurnus is described as "stiff with gold and white orichalc".[citation needed]
Orichalcum has been vaguely identified by ancient Greek authors to be either a gold–copperalloy, a form of pure copper or a copperore or various chemicals based on copper, but also copper–tin and copper–zinc alloys, or a metal or metallic alloy supposedly no longer known.[citation needed]
In later years "orichalcum" was used to describe thesulfide mineralchalcopyrite and also to describe brass. These usages are difficult to reconcile with the claims of Plato's Critias, who states that the metal was "only a name" by his time,[1] while brass and chalcopyrite were very important in the time of Plato,[citation needed] as they still are today.[citation needed]
Joseph Needham notes thatBishop Richard Watson, an 18th-century professor of chemistry, wrote of an ancient idea that there were "two sorts of brass or orichalcum". Needham also suggests that the Greeks may not have known how orichalcum was made and that they might even have had an imitation of the original.[7]
In 2015, 39 orichalcum ingots were discovered in a sunken vessel on the coast ofGela in Sicily which have tentatively been dated at2,100 years old. They were analyzed withX-ray fluorescence and found to be an alloy consisting of 75–80% copper, 15–20% zinc, and smaller percentages of nickel, lead, and iron.[8] Another cache of 47 ingots was recovered in February 2016 and found to have similar composition as measured withICP-OES andICP-MS: around 65–80% copper, 15–25% zinc, 4–7% lead, 0.5–1% nickel, and trace amounts of silver,antimony,arsenic,bismuth, and other elements.[9]
Orichalcum is first mentioned in the7th century BC byHesiod, and in theHomeric hymn dedicated toAphrodite, dated to the630s BC.[citation needed]
According to theCritias ofPlato, the inner wall surrounding the citadel of Atlantis with the Temple ofPoseidon "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 son princes of Poseidon were inscribed.[10]
Pliny the Elder points out that orichalcum had lost currency due to the mines being exhausted.Pseudo-Aristotle inDe mirabilibus auscultationibus (62) describes a type of copper that is "very shiny and white, not because there is tin mixed with it, but because some earth is combined and molten with it." This might be a reference to orichalcum obtained during the smelting of copper with the addition of "cadmia", a kind of earth formerly found on the shores of the Black Sea, which is attributed to bezinc oxide.[citation needed]
Innumismatics, the term "orichalcum" is used to refer exclusively to a type ofbrass alloy used for minting Romanas,sestertius,dupondius, andsemis coins. It is considered more valuable than copper, of which theas coin was previously made.[3]
Whether, if a person should offer a piece of gold to sale, thinking that he was only disposing of a piece of orichalcum, an honest man ought to inform him that it was really gold, or might fairly buy for a penny what was worth a thousand times as much
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