Electrum is an alloy of gold and silver, found in nature and sometimes made on purpose. Its color ranges from pale yellow to almost silvery white, depending on how much silver it contains. Ancient Egyptians used it for jewelry and monuments, and the kingdom of Lydia in western Anatolia struck the first known coins from it.
What electrum is
Gold and silver mix easily in any proportion, and native gold in nature nearly always contains some silver. When the silver content is high, the natural alloy is called electrum. Most references set the line at around 20 percent silver, with a common range of about 20 to 40 percent silver in natural specimens, though the exact boundary varies. Small amounts of copper and other metals are often present too.
The name comes from the Greek elektron, which the ancient Greeks used for both amber and this pale gold. The link is probably the shared warm, light yellow color. The modern word electricity comes from the same Greek word for amber, which builds up a static charge when rubbed.
Like gold and silver, electrum is one of the noble metals and resists corrosion. More silver makes it a little harder than pure gold, so it holds its shape better in thin forms. It can tarnish slightly if its silver content is high.
Color and appearance
Pure gold is deep yellow, and silver is white. Mixing them dilutes the gold's color. Electrum with around 20 percent silver looks pale yellow, while metal with 40 percent or more silver looks greenish-white or silvery. This is the same principle behind modern yellow gold alloys, where silver shifts the color toward green-yellow and copper shifts it toward red.
Ancient writers noted that electrum looked brighter than silver in lamplight. Pliny the Elder, writing in the first century CE, described electrum as gold with a fifth part silver.
Electrum in ancient Egypt
Egyptian goldsmiths had access to natural gold with varying silver content, mined in the Eastern Desert and Nubia. The Egyptians called this pale metal djam and distinguished it from gold. They used electrum for jewelry, amulets, vessels and decoration.
The most visible use was on monuments. Egyptian builders covered the tips (pyramidions) of some obelisks with electrum or gold so that they would catch the sun. Inscriptions from the reign of Queen Hatshepsut describe obelisks capped with electrum at Karnak.
Egyptian jewelry of all periods shows a range of gold colors, from deep yellow to pale, partly because of natural silver content and partly because goldsmiths learned to vary alloys on purpose. The ancient Egyptian jewelry page covers their work in gold, faience and stones.
The first coins: Lydia
The kingdom of Lydia, in what is now western Turkey, is usually credited with striking the first true coins in the seventh century BCE. Those early coins were made of electrum. Natural electrum was washed down from Mount Tmolus by the Pactolus River, which flowed past the Lydian capital, Sardis. The river's gold is tied to the Greek legend of King Midas, who was said to have washed his golden touch away in it.
Lydian electrum coins were stamped lumps of a set weight, many bearing a lion's head, a symbol of the Lydian royal house. Studies of these coins have found that their gold content varied and was often lower than natural electrum from the river, suggesting that some were made from deliberately mixed metal. Since the gold-silver ratio was uncertain, the value of each coin was hard to judge. Under King Croesus in the sixth century BCE, Lydia began issuing separate coins of fairly pure gold and silver, which is often described as the first bimetallic coinage.
Greek cities in Ionia and elsewhere in Asia Minor also struck electrum coins. The city of Cyzicus kept issuing electrum staters into the fourth century BCE, and these were widely traded around the Black Sea and Aegean.
Later and modern use
Electrum appears in jewelry and objects across the ancient world, including Greek, Celtic and Byzantine pieces. Some early medieval European gold coins and jewelry also had high silver contents, since the gold supply was mixed with silver.
The word electrum is rarely used in today's jewelry trade. Modern alloys with similar proportions exist, such as some green golds and low-karat yellow golds containing mostly silver as the alloy, but they are sold under their karat. A few contemporary makers and metal clay suppliers sell "electrum" for its historical appeal, usually a gold-silver alloy of stated content.
Collectors encounter electrum most often in ancient coins. Electrum coins of Lydia, Ionia and Cyzicus are studied by numismatists and held in museum collections. The Persian jewelry page covers the Achaemenid empire that absorbed Lydia after Croesus fell.
How to identify electrum
Identifying electrum and its gold content requires testing. Specific gravity gives a rough idea, since gold is about 19.3 g/cm³ and silver about 10.5 g/cm³, and alloys fall in between. Modern labs use X-ray fluorescence (XRF), which reads surface composition without damage. Ancient coins can have surface enrichment, where silver has leached out of the surface over time, making the outside look richer in gold than the interior. The specific gravity page explains hydrostatic weighing, a method also used for metals.
Frequently asked questions
Is electrum real gold?
Electrum is a mix of gold and silver. Natural electrum often contains about 60 to 80 percent gold, so it is a gold alloy, paler than pure gold.
Why did the Lydians use electrum for coins?
Natural electrum was available in the Pactolus River near the Lydian capital, Sardis. It was a convenient local source of precious metal for the first coins.
What color is electrum?
It ranges from pale yellow to greenish or silvery white. The more silver it contains, the paler it looks.
Is electrum used in jewelry today?
Rarely by that name. Modern gold alloys with high silver content are sold by karat. A few makers sell electrum for its history.