Archaeologists have uncovered 2,640- to 2,550-year-old clay moulds for casting spade coins as well as fragments of finished spade coins at Guanzhuang in Xingyang, Henan province, China. The technical characteristics of the moulds demonstrate that the site — which was part of the Eastern Zhou period (770-220 BCE) bronze foundry — functioned as a mint for producing standardized coins.
“The origins of metal coinage and the monetization of ancient economies have long been a research focus in both archaeology and economic history,” said Dr. Hao Zhao from the School of History at Zhengzhou University and colleagues.
“The earliest coins are thought to have been minted in China, Lydia (in Western Asia Minor) and India.”
“Of these, the hollow-handle spade coin (kongshoubu) minted in China is a likely candidate for the first metal coinage.”
“The spade coin was an imitation of practical metal spades, but its thin blade and small size indicate that it had no utilitarian function.”
“The earlier spade coins had a fragile, hollow socket, reminiscent of a metal shovel. This socket was transformed into a thin, flat piece in later spade coins, and over time, characters were applied to the coins to mark their denominations.”
“Several versions of spade coins circulated across the Chinese Central Plains until their abolition by the First Emperor of Qin in 221 BCE.”
“Their origin and early history, and the social dynamics under which they were developed, however, remain controversial — a situation paralleled by the century-long debate over Lydian coins.”
Dr. Zhao and co-authors from Zhengzhou University and Peking University uncovered the ancient remains from different stages of the minting process at Guanzhuang in China’s Henan province.
The mint was part of a well-organized, integrated bronze foundry run under the auspices of the Zheng State.
“Guanzhuang is located in the Central Plains of China, some 12 km south of the Yellow River,” the archaeologists said.
“Continuous excavations since 2011 have revealed the general layout of a city, which consisted of two walled and moated enclosures.”
“The city was established in c. 800 BCE and abandoned after 450 BCE.”
“Excavations between 2015 and 2019 have revealed a large craft-production zone in the centre of the outer enclosure, immediately outside the southern gate of the inner city. This area included workshops involved in bronze, ceramic, jade and bone-artifact production.”
“The bronze foundry occupied the largest area. Its main features comprise more than 2,000 pits for dumping production waste, most between 1.5 and 3 m in diameter, with a depth of 1-2.5 m.”
“Alongside ceramic sherds, these pits contained abundant remains related to bronze-casting activities, including crucibles, ladles, bronze droplets, unfinished or broken bronze artifacts, clay moulds, charcoal, and furnace fragments.”
At the site, the researchers found two fragments of finished spade coins, dubbed SP-1 and SP-2.
“Coin SP-1 is so well preserved that its complete shape can be confidently reconstructed,” they said.
“This example is a typical pointed-shoulder spade coin, with a (restored) full length of 14.3 cm, a shoulder width of 6.35 cm and a maximum thickness of 0.9 mm. The weight of the extant coin is 27.1 g.”
“Reconstructing the volume of its missing feet at around 660 mm3 (4-5g), we estimate that the original weight of SP-1 was no less than 31 g, including the weight of the clay core inside the handle.”
As is typical of the earliest spade coins, there are no inscriptions indicating either the name of the locality where the coin was cast or its face value.
“Coin SP-2 was found in the context dated to the Eastern Han Dynasty (200 CE), and hence the coin must be considered a residual find, as spade coins had long been abolished by this time,” they said.
“Of this coin, only the handle and its clay core survive. They are of exactly the same shape and size as the corresponding portions of SP-1.”
The compositional analysis shows that the copper content of SP-1 and SP-2 is 62.5 and 76.46%, respectively.
“The existence of minting activity at Guanzhuang is further documented by numerous finds of clay cores and outer moulds for casting spade coins,” the scientists said.
“All the moulds are made of reddish fine silt, which was also the primary material for producing clay moulds to cast other types of bronze products at the Guanzhuang foundry.”
Combining the evidence from radiocarbon-dating, mould style and ceramic typology, they suggest that the Guanzhuang foundry was first established around 780 BCE.
During its initial phase of around 150 years, the foundry produced predominantly ritual vessels, weapons and chariot fittings — items used in ceremonies, warfare and other aspects of elite life.
Standardized minting started from the second phase of the Guanzhuang foundry, after c. 640 BCE and no later than 550 BCE, and it made use of the workshop’s existing bronze-production capacity.
“Currently, Guanzhuang is the earliest-known archaeological mint site dated by robust radiocarbon dates in the world, and coin SP-1 is the earliest spade coin — and, more generally, the earliest Chinese coin — recovered from a secure archaeological context,” the authors said.
“The minting techniques employed at Guanzhuang are characterized by batch production and a high degree of standardization and quality control, indicating that the production of spade coins was not a small-scale, sporadic experiment, but rather a well-planned and organised process in the heartland of the Central Plains of China.”