1 Cash - Xianfeng Tongbao, Boo-joo

The Board of Revenue Mint in Beijing was one of two imperially supervised mints operating in the capital during the Xianfeng reign, the other being the Board of Works Mint. Both struggled badly by the 1850s as the Taiping Rebellion drained the treasury and disrupted copper supply lines from Yunnan. The regime's response was to debase coinage aggressively — larger denominations in iron and lead, reduced alloy quality across the board. The standard one-cash pieces like this one were the last to be debased, but even they show compositional inconsistency across the reign.

Boo-joo is the Manchu reading of the Board of Revenue mint designation.