Iwami Ginzan Silver Mine and its Cultural Landscape

The Iwami Ginzan Silver Mine in the south-west of Honshu Island is a cluster of mountains, rising to 600 m and interspersed by deep river valleys featuring the archaeological remains of large-scale mines, smelting and refining sites and mining settlements worked between the 16th and 20th centuries. The site also features routes used to transport silver ore to the coast, and port towns from where it was shipped to Korea and China. The mines contributed substantially to the overall economic development of Japan and south-east Asia in the 16th and 17th centuries, prompting the mass production of silver and gold in Japan. The mining area is now heavily wooded. Included in the site are fortresses, shrines, parts of Kaidô transport routes to the coast, and three port towns, Tomogaura, Okidomari and Yunotsu, from where the ore was shipped.

Historical context

According to the dossier, although there is some evidence to suggest that the silver seams were known in the 14th century, the Iwami Ginzan Silver bearing seams were ‘discovered' in 1526, and almost immediately developed by Kamiya Jutei, a powerful merchant of Hakata, then the largest trading port in Japan. Jutei operated under the protection of the Ôuchi family, a feudal clan who controlled the Iwami region and whose wealth was based on trade with China and Korea. Around 1533 the more efficient ‘cupellation' smelting technique was introduced to the mines possibly from Korea, and this dramatically increased the output of the mines to the extent that the in the late 1530s, the amount of silver which was offered as the tribute to the Ôuchi Family increased from 16 to 80 kg per year.

In the 1530s and 1540s, the Ôuchi family's authority of the silver mines was repeatedly challenged by neighbouring land owners who fought for control of the highly profitable mines. The three fortresses around the mines date from this time. In the 1550s the Amago family took control for ten years followed by the Môri family in 1561. The Môri family established their vassals in the surrounding area and created two new routes to the newly developed ports of Yunotsu and Okidomari.

After a series of national wars over the next twenty years, Tokugawa Ieyasu, became the ultimate victor. In 1600 he took over the seat of power, establishing the Tokugawa Edo Shogunate and expropriated gold mines and silver mines throughout Japan. Okubo Nagayasu was appointed to administer the mines and developed new shafts and increased silver production. The mine business was run by mining directors called yamashi, who paid silver as commission to the Edo Shogunate. Yasuhara Dembei, the yamashi who operated the Kamaya-mabu and other mine shafts under contract with the Tokugawa Family around 1600-1602, paid 13,500 kg of silver in one year to the Edo Shogunate. The digging of silver ore was carried out by miners who were employed under contract to the yamashi although few details are available to suggest whether miners were indentured or self regulated.

The early 17th century was the heyday of the mines with as many as ten thousand people employed. The Dutch and English furthered international trade and within Japan relatively settled times led to the flourishing of towns which further increased demand for silver. Silver production was operated by the private capital of the yamashi.

In the mid 17th century administration of the silver mine and its surrounding area came under the control of a magistrate deployed by the central national government, the Edo Shogunate, and this further increased output. Few specific silver production figures are provided in the nomination dossier and no quantitative information is available to provide a clearer impression of the impact of the mine on the economies of the wider region.

The silver production at the Iwami Ginzan Silver Mine reached its peak in the 1620s-1640s and started to decline gradually after that. As mine shafts were dug deeper into the ground, it became more difficult to work and more costly to drain out water, making silver production less profitable. In 1691, 63 of a total of 92 mine shafts were closed; in 1729, 74 of a total of 129 mine shafts were closed; and in 1823, 247 of a total of 279 mine shafts were not in operation. The silver production that had averaged 1,000 to 2,000 kg annually in the late 17th century decreased to 100 kg or so in the mid-19th century.

After the Edo Shogunate fell in 1868, the Iwami Ginzan Silver Mine was privatized in 1869 by the new national government. In 1887, a private company named Fujitagumi resumed operation of the silver mine and renamed it Ômori Kôzan (Ômori mine). In 1895, a refinery was constructed at Shimizudani, introducing western technology, but it was closed after little more than one year. In its place, another refinery was constructed at Kôjidani at the western foot of Mount Yôgaisan, where smelting and refining, mainly of copper but also of gold and silver, was carried out. However, because the price of copper dropped and cheap copper started to be imported after World War I, the mine was forced to close in 1923. Later in 1942, an attempt was made to reopen the mine to meet the demand for metal during World War II, but this failed due to damage from a typhoon in 1943.

Details of the history of the mines in relation to its political context cannot be matched by equivalent detail for the history of technological transfer to the rapidly developing mines in Japan. The transfer of the ‘cupellation' to other silver mines in Japan is noted in the dossier but little is available on the impact of other mining and smelting techniques. Evidence for how cupellation was transferred to Japan, how it spread within Japan, the origins of this technique as used in Japan, and its relationship to the cupellation technique known in the west since antiquity, are not available.

The dossier does not relate the technology to archaeological evidence - although as yet very little of the mines have been explored. Thus it is not possible to detail neither how technology developed within Japan in its long period of isolation from Western influences nor whether this was pioneering, as suggested in the dossier. Nor can the history of Iwami Ginzan's role as perhaps the major supplier of newly mined silver in Japan and its impact on its commerce and that of its neighbours, be set down. There appears to be strong evidence that Japanese silver exports in the 17th century increased to compensate for the decline of those in Latin America, but supporting evidence is unavailable.