What is the “Sado Island Gold Mines”?

Blessed with nature where crested ibis soar in the sky, Sado Island boasted abundant mineral resources. From the 17th to the middle of the 19th century, mines were developed at full scale, making it widely known as the gold-producing island.
During this period, mechanization rapidly progressed in other parts of the world, but the flow of modern technology and knowledge from overseas was restricted due to Japan’s seclusion policy. Under these circumstances, traditional unmechanized mining methods advanced to a high level, enabling mining, smelting, and refining to continue being processed by hand on Sado over 250 years. To improve the efficiency of manual mining operations, the Tokugawa Shogunate established management system along with social organization, which made it possible to produce considerable quantities of high-quality gold for global standards in the 17th century. This is testified by the well-preserved remains of mining sites and settlements that are still kept in good condition, which can be seen as an exceptional example of cultural property in the Asian context.
This was globally recognized as the outstanding universal value and the “Sado Island Gold Mines” was inscribed as a UNESCO World Cultural Heritage Site on July 27, 2024.

The “Sado Island Gold Mines” consists of two areas with different types of deposit: the Nishimikawa Placer Gold Mine and the Aikawa-Tsurushi Gold and Silver Mine.

Gold production on Sado Island was first mentioned in the “Tales of Times Now Past,” a collection of tales complied in the 12th century. The site is believed to refer to the Nishimikawa Placer Gold Mine, suggesting that it is the oldest placer gold mine on Sado. In order to efficiently obtain “visible gold,” or placer gold, the “Onagashi” (great flow) method was used during the Edo period. Traces of scraped mountain surfaces, as well as reservoirs and waterways used in “Onagashi” are well preserved around the settlements.

Conversely, the Aikawa-Tsurushi Gold and Silver Mine was developed to extract “invisible gold,” or gold contained in gold and silver veins in solid bedrock. Various technologies and production processes were developed for crushing, finely griding, and chemically processing mined ore. The Aikawa-Tsurushi Gold and Silver Mine consists of two areas: the Tsurushi Silver Mine and the Aikawa Gold and Silver Mine.

The Tsurushi Silver Mine, discovered in 1542, was the largest silver mine on Sado. More than 600 traces of excavation were identified, showing different types of excavation techniques. Also, new technologies involving cupellation (a technology to extract silver from ore by adding lead) were introduced by engineers from Iwami Silver Mine (now a UNESCO World Heritage Site in Shimane Prefecture). This technology laid the foundation for the gold production that would later begin in Aikawa.

Full-scale development in the Aikawa Gold and Silver Mine started in the beginning of the 17th century. Under the direct rule of the Tokugawa Shogunate, a large amount of gold and silver mined on the island were minted into koban coins and supported the Shogunate’s finances.
Sado is the only place in Japan where the entire process from mining through minting was conducted in a single place. These processes were depicted in detail in more than 100 surviving picture scrolls. Archaeological documents and books on mining technology help us understand the production methods and daily lives of people in the mining community.

Other than these physical evidence for gold production technologies, diverse cultures which were deeply connected to mining society can be seen in various places on Sado.