1 Cash - Xianfeng Tongbao, Boo-san

The Boo-san mint — romanized from the Manchu designation for Shanxi province — was among the smaller Board of Revenue satellite operations, and its output during the Xianfeng period was already strained before the Taiping Rebellion began consuming copper supplies and disrupting transport routes from the southern mines. By the mid-1850s, the central government was authorizing increasingly debased multi-cash denominations precisely because standard cash production had become economically unsustainable. This 1-cash piece predates that collapse, but only just.