Electrum

Electrum occurs both naturally, panned as pale gold from riverbeds, and artificially, alloyed on purpose once smiths learned to control the ratio. The natural form found in the Pactolus river in Lydia supplied the metal for what are generally considered the world's first true coins, struck in Lydia and the neighboring Ionian Greek cities in the seventh century BCE. Because the gold-to-silver ratio in natural electrum was not consistent from one nugget to the next, those early coins were valued by weight and stamp rather than by a fixed metal content, an uncertainty that later Lydian and Persian rulers moved to solve by minting separate pure gold and pure silver coinage instead.

Pliny the Elder and other ancient writers called it "white gold" for its pale color, distinct from the yellow of unalloyed gold, and treated it as its own recognized metal rather than as merely impure gold. Modern jewelers still use the word for gold-silver alloys made on purpose, though the deliberately proportioned kind has little to do with the variable natural metal the ancient world worked with.

Egyptian builders capped pyramids and obelisks with electrum, most famously the small pyramidion, the capstone that crowned a pyramid's peak. Amenemhat III's pyramidion at Dahshur is among the surviving examples, and obelisk tips were finished the same way, so that the very top of the monument, the point that first and last caught the sun, was faced in a metal pale enough to gleam rather than the duller gold-red of gold alone. Some later esoteric readings of Egyptian metal use interpret the electrum cap as a union of the solar principle carried by gold and a lunar or reflective principle carried by silver, though this is a modern gloss on the practice rather than a claim the Egyptian sources themselves make explicit, and the atlas records it as such.

Electrum also appears in temple fittings, ritual vessels and personal ornament throughout the Egyptian, Mesopotamian and Mycenaean worlds, valued for a brilliance distinct from either of its parent metals and for the fact that a naturally occurring alloy needed no smith's skill to combine, only the skill to work it once found.