Silver has been known since ancient times, but its usage is more recent than that of gold. The cupellation process is believed to have been developed in the 6th or 7th century BC while the metal itself was used as a currency as early as 5000 BC. Use of the word silver as a synonym for money dates back to the Middle Ages. It was during this period that silver mines began to be exploited throughout Europe. The discovery of silver deposits in the ‘New World’ after 1492 had a huge impact on the role of silver throughout the world and mining of silver thereafter dramatically eclipsed anything that had come before. Between 1500 and 1800, Bolivia, Peru and Mexico accounted for over 85 percent of world production and trade. The name of the metal is derived from the Greek αργυρος, which means shiny. The name of the pound sterling (£) reflects the fact it originally represented the value of one pound weight of sterling silver.