Sado mine

The Sado gold mine (佐渡金山) is a generic term for gold and silver mines which were once located on the island of Sado in Niigata Prefecture, Japan. Among these mines, the Aikawa Gold and Silver Mine (相川金銀山) was the largest and was in operation until the modern era. The Sado Gold and Silver Mine was inscribed on Japan's World Heritage Tentative List under the title "The Sado Complex of Heritage Mines, Primarily Gold Mines" in 2010.

History
The origins of mining on Sado are unknown; however, surface deposits of native gold and argentite in quartz substrate have been known since at least the Heian period. In the Heian period Konjaku Monogatarishū (Tales of Ancient and Modern Japan), there is an anecdote about a trip to Sado Province to mine for gold sand.

It seems that gold was known to be produced on Sado Island, at least in the form of gold sand, etc., by the late 11th century, when the Konjaku Monogatarishū is estimated to have been written. A similar anecdote is also found in the Uji Shūi Monogatari (Gleanings from Uji Dainagon Monogatari) written in the first half of the 13th century.

There is a popular mythology that the mines of Sado were the secret source of wealth for the Sengoku period warlord Uesugi Kenshin, which was widely popularized by the novelist Jirō Nitta; however, during this period, Sado was controlled by the Honma clan, and it was only after the Honma were defeated in 1589 by Kenshin's successor Uesugi Kagekatsu that the island and its mines came under the control of the Uesugi clan.

Following the establishment of the Tokugawa shogunate, the island became tenryō territory under the direct control of the Shogunate. This corresponded with the discovery of a new gold vein in 1601 in what would later become the Aikawa gold and silver mine. During its peak production period, from around 1615 to 1645, the mines on Sado produced an estimated 400 kilograms of gold and 37.5 tons of silver per year, making Sado one of the largest producers of gold and silver in the world, and forming a substantial portion of the income for the Tokugawa shogunate. During the early period, the mine workers were paid handsomely and the surrounding towns were prosperous. However, by the later half of the Edo period, extraction was becoming increasingly difficult due to water ingression from natural springs and into the tunnels following veins of ore underneath the seabed. The shogunate supplemented the local workforce by bringing in convicted criminals and indigents from the streets of Edo. Conditions for these forced laborers was extremely harsh, as they were used for the most dangerous tasks and for the heavy labor involved in draining the mines, and a sentence to the Sado mines was a life sentence.

By the Meiji restoration, production had dropped considerably and the new Meiji government sold the mines to a consortium led by Mitsubishi in 1896. Using imported machinery and modern mining techniques, including cableways, vertical shafts and improved extraction technology, the Aikawa mine was able to increase production to 1500 kilograms of gold and 25 tons of silver annually by 1940.

In February 1939, the Sado Mine first recruited workers on the Korean Peninsula to fill the shortage of Japanese laborers for the draft. At the time, the Korean Peninsula was part of Japan's territory. The recruiting area was mainly in Chungcheongnam-do (South Chungcheong Province), and the recruitment was so popular that for every 20 people recruited per village, there were 40 applicants. It is believed that the drought in South Korea in 1938 was one of the reasons for the high number of applicants. However, most of them only applied because they longed for life on the Japanese mainland, and many of them fled as soon as they arrived in Shimonoseki or Osaka. Between February 1939 and the last recruitment in March 1945, a total of 1,200 Korean workers came to the Sado Mine (not including their accompanying families).

However, the actual number of Korean workers working at the Sado Mine was only about half of that number: as of the end of May 1943, the number of Korean workers who came to the Sado Mine was 1005, of which 10 died, 148 escaped, 6 were repatriated for public injuries, 30 for personal illness, 25 for bad conduct, 72 were furloughed, and 130 transferred out. The actual number of Korean workers was 584.

The average number of working days for a Korean worker at that time was about 28 days, and the average monthly income was 66.77 yen. There was also an incentive for full-time work. In the event of death, the company paid up to 300 yen. In addition, a school was set up by the company to provide Japanese language education for those who wanted to improve their Japanese.

However, since food, bedding, and work clothes were not free, Korean workers sometimes went on strike demanding better treatment, and the Sado Mining Works had a hard time improving their conditions.

In 1945, the Sado Mine did not perform well in copper mining and there was an excess of Korean workers. Therefore, in August of the same year, the Sado Mine dispatched 189 workers to Saitama Prefecture as the first group of volunteer workers and 219 workers to Fukushima Prefecture as the second group of volunteer workers, for a total of 408 workers.

On August 15, 1945, the Pacific War ended with Japan's defeat. As of August 15, 244 Koreans were working at the Sado Mine. Immediately after the defeat, Koreans who had been sent to the Sado Mine from Sado as the first and second “special volunteer corps” returned to the mine. The Fukushima group arrived on August 26, and the Saitama group on August 27 and 28, for a total of 319 workers. The original number of 408 Koreans dispatched was 408, but during this period, 89 Koreans were reported missing. These were those who escaped while in Saitama or Fukushima, or refused to return to Sado Island after August 15.

In addition, due to the defeat in the war, there was a succession of those who fled Sado and those who returned to the mines, and by the end of August, the number of Koreans at the Sado Mine reached 573. 7 new Koreans fled from the Sado Mine between August 15 and September 11, while 27 returned to the mines.

Mining operations had been reduced by a large scale by 1952. The final mining operations were stopped on March 31, 1989.

Current situation
Since the closure of the mine, efforts have been made to turn some of the sites, particularly the Aikawa mine into tourist attraction and to preserve some of the buildings and facilities as part of Japan's industrial heritage. Of the estimated 400 km of tunnels in the Aikawa Mine, about 300 m have been opened to the public as a museum, with mannequins and explanatory dioramas to explain the history of the facility.

The Sado gold mine was designated a National Historic Site of Japan in 1994, with the area under protection expanded in 2017.