electrum

noun3

1. •
   An alloy of gold and silver, used by the ancients; now specifically a natural alloy with between 20 and 50 per cent silver.

   • A natural alloy containing more than 20 per cent silver is called electrum, and was regarded by the ancients as a different metal from gold. — 2002
2. •
   German silver plate.
3. •
   (no longer used) Amber.