1 Cash - Xianfeng Tongbao, Boo-chuwan, with crescent

The Board of Revenue Mint at Chengdu operated under chronic supply pressure during the Xianfeng period, when the Taiping Rebellion severed key copper routes and forced provincial mints to substitute brass — a departure from the traditional cast bronze that collectors now use to distinguish Xianfeng issues by metal alone. The crescent mark on this piece is a reverse control symbol used to track output by furnace or shift, a bookkeeping device that inadvertently created the variety distinctions Hartill later catalogued.

Chengdu issues from this window are frequently better preserved than contemporary metropolitan output, Sichuan's relative insulation from the rebellion's worst disruptions keeping local commerce — and local coin handling — comparatively subdued.