The ore consists of microscopic particles of free gold and/or electrum, gold selenide, and gold-bearing sulfides found in a banded quartz vein five to 22 ft wide.
The very first coins were made from electrum (an alloy of gold and silver), followed by pure silver, the most commonly found valuable metal in the region.
A rich foundation deposit from this era yielded more than a thousand items, including what may be the earliest coins made from the silver-gold alloy electrum.