Electrum is a natural alloy of gold and silver, with trace amounts of copper and other metals. The man-made gold and silver alloy with a similar composition is called green gold.
Electrum Chemical Composition
Electrum composition depends on its origin. Modern electrum from Western Anatolia is 70-90% gold, but the alloy ranges anywhere from 20-80% gold and 20-80% silver, often with copper, iron, bismuth, and palladium. Electrum coins contain less gold than the natural alloy, so it’s believed the ancients diluted the source material with silver or other metals to conserve profit.
Man-made electrum or green gold is approximately 18K gold, containing at least 20% silver. Sometimes German silver is called electrum, but the name refers to its color and not its composition. German silver contains around 60% copper, 20% nickel, and 20% zinc.
What Color Is Electrum?
Electrum does not have a fixed composition, so it displays a range of colors ranging from nearly silver, like white gold, to deep yellow, like 18 karat yellow gold. If it contains enough copper, it has a faint reddish-gold color, like brass. Although the ancients called electrum “white gold,” this was to distinguish it from refined gold. Modern white gold often has a different composition and appearance from electrum.
The man-made version of electrum is called green gold. It consists of gold and silver and does appear faintly yellowish green. However, gold alloys that appear very green contain cadmium. The addition of 2% cadmium produces a light green color, while 4% cadmium yields a deep green color. Alloying with copper darkens the color of the metal.
Electrum Properties
Electrum consists of noble metals, so it resists oxidation and corrosion. It has high thermal and electrical conductivity. It is ductile, malleable, and polishes to a mirror-like finish.
Electrum Uses
Because electrum occurs naturally, it was available to ancient people. The beautiful metal was soft enough to work, yet strong enough to hold its shape. It was used to make jewelry, ornaments, and drinking vessels. The Egyptians used the metal for decoration and coating obelisks and the pyramidions atop pyramids, dating back as early as the third millennium BC. The first metal coins in the western world were electrum, dating to at least 625-600 BC in Lydia and Greece.
Where to Find Electrum
If you want to see electrum, you’ll need to either visit a museum or mine or else win the Nobel Prize. Since 1980, the Nobel Prize medal is made of 18K green gold (man-made electrum) plated with 24K (pure) gold. Originally, electrum came from Lydia, near the Pactolus River, which is a tributary of the Hermus in Asia Minor. Today, ancient Lydia is called the Gediz Nehriin in Turkey. Today, most electrum comes from Anatolia, although a smaller amount occurs in Nevada, in the USA.
References
- Chisholm, Hugh, ed. (1911). “Electrum, Electron” . Encyclopædia Britannica. 9 (11th ed.). Cambridge University Press.
- Emsley, John (2003) Nature’s Building Blocks: An A–Z Guide to the Elements. Oxford University Press. ISBN 0198503407.
- Kurke, Leslie (1999). Coins, Bodies, Games, and Gold: The Politics of Meaning in Archaic Greece. Princeton University Press. ISBN 0691007365.