Copper 铜 (also 红铜)

Copper is the first metal in the metal age of East Asia and remained the metal of highest cultural value. Pure copper is relatively soft and therefore not particularly useful. Alloyed with arsenic or tin, however, it becomes considerably harder and is called bronze. Bronze objects can be cast and produced on a large scale. Alloyed with zinc, copper becomes brass, again a rather soft metal, but with the advantage of being malleable. Brass objects can be cast and hammered into a great variety of shapes.

History up to the investigated period

In the Southwest and highland Southeast Asia, metallurgy in the region began with copper, soon followed by tin bronze. The first objects have been dated to about 1500-1300 BCE in excavations in northern central Yunnan, northern Vietnam and northern Thailand (contested earlier datings exist for Ban Chiang in northern Thailand – as early as 2100 BCE). The widespread use of large bronze drums in the first millennium BCE reflects copper and tin exploitation on a considerable scale, bronze casting metallurgy and a metallurgical cultural zone that extended from Sichuan across the Chinese Southwest, and the Southeast-Asian highlands.

Only very few sites of bronze-age mining have been identified, mainly Ban Chiang in northern Thailand. The archaeological record improves in the period roughly coinciding with the Han dynasty (206 BCE – 221 CE). Mining and metal production is attested for Gejiu 个旧, and major identified metallurgical centres that focussed on casting bronze were the Dian 滇 kingdom, the Hanoi, and the Zhaotong 昭通 areas. In the same period, mining is attested in Zhaotong and in the Hongwangshan massif in southern Dongchuan 东川. As far as I know, the metal sources of Hanoi are not identified. Similarly, copper mining in central and central western Yunnan is certain, but the sites are uncertain. Tin may have been worked at Gejiu, but hard evidence is not available.

Both the historical and the archaeological records provide little specific information for the subsequent centuries. The Nanzhao 南诏 and Dali 大理 kingdoms clearly produced large quantities of metal objects, still retaining a main focus on bronze for religious objects, but also working iron, silver and gold. The mining sites are unclear. The history of mining through the Yuan and into the Ming period fell into oblivion as well because no identified and dated sites have been found and no written records exist.

The Ming-Qing period

Historical records on copper mines begin only in the later Ming period. Official records mention mines, often only as place names without further information on the exploitations. A number of mines are known by name, mainly in central Yunnan, but their importance and in many cases even their geo-location is uncertain. The famous traveller Xu Xiake 徐霞客 (original name Xu Hongzu 徐弘祖, 1587–1641), travelled to central, central western and northeastern Yunnan in 1638-1639 and noted the roads and the intensity of transport into the copper mining region of southern Dongchuan. His account is the only specific record that documents the importance of the mines that Qing records identify as Tangdan 汤丹.
More detailed official records set in from 1739, when Yunnan province became the supplier of copper for the imperial mints. From this juncture, official sources, such as local gazetteers and the compendium Diannan kuangchan tulue 滇南矿产图略, contain lists of licensed copper mines. These identify some 70 mining areas by name, with annual production quotas for some 50 mines.

The system governing the procurement of copper for the mints in theory required mines to sell their entire output to government agents, offering the advantage of advance payments but the practically unmanageable conditions of low and immutable “official prices” (guanjia 官价) as well as underpaid delivery to the government stores. The fact that the rules remained largely stable and the system worked for over a century reflects that actual operations never fully abided by the rules. As the concern in this context is the reliability of the records with respect to the sites and their productivity, we can be certain that recorded sites in fact existed, although in certain cases a mining site might appear under more than one name. This occurred when a mine was officially closed as exhausted and later reopened under a new name, or when existing names of a site were confused with names of individual mines. With respect to the scale of exploitations, the production quotas can only be used as a relative indication. They presumably reflect expected or actual productivity at the time when they were set, but might increasingly diverge from actual outputs as time went on. I may add that written records invariably complain of difficulties and report falling outputs of even total exhaustion (洞老山空). These statements have to be taken with a large pinch of salt, as these were the only possible arguments for increasing the “official prices” or for condoning the failure of fulfilling the quota.

In short, records on copper mines are relatively dense and with regard to sites probably exhaustive and reliable for Yunnan from the mid-18th to the mid-19th century. Records for copper mines in Sichuan 四川 are less detailed, but also available. For copper mines in northern Vietnam, systematic records become available from the 19th century.

It should be noted that output figures refer to quotas that seemingly remained stable. We expect that these quotas may have come relatively close to actual outputs at the time when they were set. Over the subsequent period, quotas either remain stable or were gradually reduced. While an initial peak followed by gradual decline is possible and even probable, an increasing divergence between recorded and actual amounts is almost inevitable. For this reason, our knowledge on the productivity of specific copper mines as well as global outputs remains sketchy.

With regard to ores, mines, and smelting technologies, Diannan kuangchan tulue 滇南矿产图略 of 1844 and a handful of other records of the same and of the late traditional period are the only sources specific to the region. Tiangong kaiwu 天工开物 of 1637 is the core and only source for late Ming technologies of uncertain geographic origin.

Research questions:

To summarise: sources about copper mining in Southwestern China of the Qing period are the richest body of materials on any aspect of Chinese historical metallurgy. Using these records, we can identify the mining areas from the 18th century and assess the intensity of their exploitation. Based on early 19th century records, we also have materials that permit the reconstruction of the types of ores that were exploited (Vogel 2008), and the technologies employed in mining, in ore dressing, and in smelting in the Yunnanese and presumably in the southwestern copper mining industry. Specific processes and process steps, however, are not understood, such as the treatment of copper-silver ores. Moreover, the history prior to the 18th century is relatively unexplored.

While indirect evidence, such as the widespread use of brass utensils in the Ming period, documents the expansion of copper mining, the mining areas and the metallurgical technologies are not identified beyond their broadest outlines.

Research in this project focuses on the identification and assessment of copper mining and smelting sites. The focus is on remains and oral traditions as well as on identifying sites before the relatively well-documented period from the early 18th century.