A gold coin is a coin that is made mostly or entirely of gold. Most gold coins minted since 1800 are 90–92% gold (22‑karat), while most of today's gold bullion coins are pure gold, such as the Britannia, Canadian Maple Leaf, and American Buffalo. Alloyed gold coins, like the American Gold Eagle and South African Krugerrand, are typically 91.7% gold by weight, with the remainder being silver and copper. Traditionally (up to about the 1930s), gold coins have been circulation coins, including coin-like bracteates and dinars. In recent decades, however, gold coins are mainly produced as bullion coins for investors and as commemorative coins for collectors. While modern gold coins are still legal tender, they are not observed in everyday financial transactions, as the metal value normally exceeds the nominal value. For example, the American Gold Eagle has a denomination of 10 USD, but a metal value of more than $800 USD (being around a half an ounce). The gold reserves of central banks are dominated by gold bars, but gold coins may occasionally contribute. Gold has been used as money for many reasons. It is fungible, with a low spread between the prices to buy and sell. Gold is also easily transportable, as it has a high value-to-weight ratio compared to other commodities such as silver. Gold can be re-coined, divided into smaller units, or melted into larger units such as gold bars, without destroying its metal value. The density of gold is higher than most other metals, making it difficult to pass counterfeits. Additionally, gold is extremely unreactive chemically: it does not tarnish or corrode over time. From Wikipedia
