Xianfeng Yuanbao, Board of Revenue Mint, Value 100 'Da Yang' Large Specimen

This is a rare and heavy cast copper-alloy cash coin from the Qing Dynasty, specifically issued during the reign of the Xianfeng Emperor (1851-1861). The item is a 'Dang Bai' (Value 100) denomination, commonly referred to as Xianfeng Yuanbao. It measures 55mm in diameter and weighs 61.43g, placing it firmly in the prestigious 'Da Yang' (Large Specimen) and 'Hou Rou' (Thick Body) categories, as standard issues typically weigh between 40-55g. The obverse side (not fully visible but implied by the type) features the four characters 'Xian Feng Yuan Bao' in regular script. The reverse side seen here features the denomination 'Dang Bai' (Value One Hundred) written vertically and the Manchu characters for the Board of Revenue Mint (Boo Chiowan) placed horizontally. The coin exhibits a rich, natural reddish-brown copper tone with significant areas of vibrant green malachite oxidation (patina) accumulated in the recessed fields. The calligraphy is deep and well-defined, indicating a high-quality strike or cast. There is evidence of minor circulation wear on the raised outer rim and high points of the characters, but the structural integrity is excellent with no signs of cracks or modern repairs. The squared central hole is well-formed with clean edges characteristic of mid-19th-century minting technology from the central Beijing mint.