Heaviest coin for circulation

The heaviest coin ever is a rectangular Swedish 10-daler copper plate dated 1644 which weighed 19.7 kg (43 lb) and measured 30 x 70 cm (12 x 28 in).

Known as plåtmynt, these large, square-shaped coins or plates were very common in Sweden up until 1776. Of the approximately 25,500 10-daler pieces minted between 1644 and 1655, just seven exist today. The plate money ranged in value from 0.5, 1, 2, 3, 4, 5, 8 and 10 dalers. As Sweden was rich in copper, the plates were minted at their full-weight, equivalent to their values in silver money. The copper used to come mainly from the Fau Copper Mine which was first mined by vikings. Because of their heavy weight, these were often stored in warehouses and the depositor issued a receipt that often circulated, leading to one of the earliest instances of paper currency.

The size of the 10 daler coin is equivalent to three GWR books placed on a flat surface side by side.