Orichalcum

Orichalcum or aurichalcum, oreikhalkos is the name of a metal or two different metals. Old writings from ancient Greece talk about orichalcum and the Romans made coins out of a metal they called orichalcum, but they might not have been the same metal. People were not sure exactly what it was, until 2015 a shipwreck was found whose cargo contained ingots of orichalcum.
Initially some scholars thought orichalcum was the ancient Greek name for platinum. Others thought it was an alloy, or mixture, of copper and either gold, tin, or zinc. Scientists examined Roman coins and found a mixture of copper and zinc.
The chemical analysis of the ingots found in the 2015 shipwreck revealed orichalcum is high quality brass. Brass is an alloy of copper and zinc, and while the ancient Greeks did not know metallic zinc, they knew zinc-containing ores, and the description that orichalcum has similar colour and shine as gold, fits well to the properties of brass. While brass is not exactly a precious metal, it does not corrode and it is widely used on jewelry, marine instruments and medical instruments. Goldsmiths and jewellers describe brass as "mahogany of metals".
Name
The name orichalcum is from the Greek word for "mountain copper" or "mountain metal."
Some people think name aurichalcum comes from the word aurum for "gold," but it does not.
Greek orichalcum
In general, when ancient Greek writers wrote about orichalcum, they said it was a metal that looked like gold but that they did not know much else about it. To Homer, Hesiod and Plato, orichalcum was a metal from much earlier times that did not exist in their own time and place.
In one of the Homeric Hymns, Homer writes about orichalcum earrings. He says the goddess Aphrodite wears them. Hesiod writes about orichalcum greaves, which are leg armor. Neither writer was talking about his own time and place.
Plato wrote about orichalcum in his book Critias. In the book, Plato says orichalchum was in the ground of the legendary island of Atlantis. To the Atlanteans, it was the second-most-valuable metal, after gold. Plato says the Atlanteans put orichalcum on their city walls and temples. Plato calls orichalcum "only a name" in his own time, meaning he did not think he had ever seen orichalcum.
Roman orichalcum
The ancient Romans also had a metal that they called orichalcum. Around the time the Roman Republic ended and the Roman Empire started, the Romans stopped making coins out of bronze and started making them out of orichalcum: asses coins, sestertii coins, dupondii coins and semisses coins.
Roman orichalcum does corrode over time, the way iron rusts and silver tarnishes.
Making orichalcum
Scientists analyzed Roman coins and saw they were made of copper and zinc. During the early days of the Roman Empire, Romans invented a better way to make zinc-copper alloys. This way is called cementation. To do it, the metalworker has to heat the zinc and copper to exactly the correct temperature. Then there can be as much as 30% zinc in the orichalcum.
In fiction
Orichalcum appears in many works of fiction, especially stories about Atlantis. It is in television shows, for example The Mysterious Cities of Gold and Nadia: The Secret of Blue Water. It is in video games, for example Castlevania: Curse of Darkness and Elder Scrolls.