If the Olympic gold medal was made of real gold, it would be worth a small fortune.

This year's medals weigh between 375 and 400 grams, CoinWeek reports. They are the largest and heaviest medals in Olympic history. If the gold medal contained 400 grams of actual gold, it would be worth nearly $21,000 (using a spot gold price of $52.20 a gram).

But it's been 100 years since the Olympic games gave solid gold medals to victorious athletes. Now, the gold medal is a mere 1.34% gold and 92.5% silver, with the rest made up of copper, according to Dillon Gage, one of the country's largest precious metals dealers.

The silver medal is truer to form, containing 92.5% silver and the rest copper. The bronze medal is 97% copper, 2.5% zinc and 0.5% tin.

So how much are these medals worth? Using some back-of-the-envelope​ calculations, the gold medal is worth around $650. The silver medal is worth about $330 and the bronze medal is worth just $3.

Not that any of these athletes would actually sell their medals, right? No, they do. In fact, a gold medal worn by Mark Wells, part of the 1980 U.S. men's "Miracle on Ice" hockey team, was auctioned for $310,700 two years ago, CoinWeek reports. Wells sold his medal years earlier to pay for medical expenses related to a rare genetic disease.

Most of the metal used in this year's medals came from the United States. Miner Rio Tinto (RIO) said the majority of the metal came from its Kennecott copper mine in Utah, and the rest came from its Oyu Tolgoi project in Mongolia. More than eight tonnes of Rio Tinto metal was used to make the medals. The medals are 85 millimeters in diameter and 7 millimeters thick.

The Royal Mint in South Wales made the 2,300 medals that will be awarded in this year's Olympic games.

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