Lost cities / archaeology / ancient history

A fairly basic mistake to make when minting coins, I guess:

The coin features a portrait of the bearded and crowned Henry III on his throne, and about 52,000 of them were minted.

It became apparent they were financially unviable because the value of the coin was less than its weight in gold and almost all were melted down.

https://www.theguardian.com/uk-news/2022/jan/24/devon-detectorist-13th-century-gold-coin-sold