Biting medals is a press-pleasing tradition. It is thought to be inspired by the US Gold Rush when miners needed to check nuggets for soft gold as opposed to fool’s gold.
Weighing between 500g and 800g, gold medals are actually made from silver coated with at least 6g of pure gold. A ‘gold’ medal’s value depends on global markets, but those issued in Rio in 2016 were estimated to be worth over £360 each.
Medals for the delayed 2020 Tokyo Olympics are made from recycled metals. The host country’s mint is responsible for making medals, following International Olympic Committee specifications. Solid gold medals haven't been handed out since 1912.
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Dr Emma Davies is a science writer and editor with a PhD in food chemistry from the University of Leeds. She writes about all aspects of chemistry, from food and the environment to toxicology and regulatory science.