Coin tree of brass Guangxu zhongbao coins
Board of Revenue Mint, Beijing, China
Qing dynasty, around AD 1905
How Chinese coins were cast in moulds
Until the 1880s, all Chinese coins were cast in moulds, while in Europe striking coins using coin dies was more common.
Specially-made master coins and master moulds were used to make impressions in the moulds. The moulds were stacked up and molten metal was poured in. When the metal had cooled, the moulds were broken open and the coins were removed.
When the moulds were opened, the coins were still attached to the metal that had cooled in the casting gullies. The resemblance to branches at this stage led people to call them 'coin trees'.
The next step was to break all the coins off the branches and to file down the edges. The most effective method was to thread the coins onto a square-sectioned rod and file down the edges of hundreds of coins at a time. Some people believe that this was the reason why Chinese cash coins had a square hole in the middle.
J. Williams (ed.), Money: a history (London, The British Museum Press, 1997)