Since the 1912 Summer Olympic Games in Stockholm, gold medals have been composed primarily of which metal?

The top three finishers of each Olympic competition are awarded the gold, silver, and bronze medals, respectively. While the name seems to imply it, Olympic gold medals are not 100% gold. At one time the prize given to the first-place finisher in each competition was solid gold, but now Olympic gold medals are made mostly from silver. For that matter, the second-place silver medals aren't always 100% silver either, though they do contain the same amount of silver as the gold medal. As for the third-place bronze medal, it is made of exactly what its name claims.

The last series of medals made of solid gold were awarded at the 1912 Summer Olympic Games in Stockholm, Sweden. Traditionally, Olympic gold medals are required to be made from at least 92.5% silver, and must contain a minimum of 6 grams of gold.

The specific composition and design of Olympic medals is determined by the host city's organizing committee. However, minimum standards must be maintained:

Gold and silver medals are at least 92.5% silver.

Gold medals must be plated with at least 6 grams (0.22 oz) of gold.

All Olympic medals must be at least 3 mm (0.19 in) thick and at least 60 mm (2.36 in) in diameter. Bronze medals are bronze, an alloy of copper and usually tin.

For example, the silver medals at the 2018 Pyeongchang Winter Olympics had a purity of 99.9%. A gold medal was a silver medal plated with 6 grams of gold, while the bronze as made of an alloy of 90% copper and 10% zinc.