Ashio Copper Mine – Nikko, Japan - Atlas Obscura

Ashio Copper Mine

Nikko, Japan

The site of Japan's first major environmental disaster. 

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Every student in Japan sooner or later learns about the Ashio Copper Mine in history class. It was the site of Japan’s first major environmental disaster, which filled the surrounding area with poisonous gases and polluted water during the late 19th-century. Due to the lack of scientific analysis, the exact extent of damage is still unknown, but over 1,000 people died of cadmium poisoning in the following years. 

Originally discovered in 1550, Mount Ashio became a government-run quarry after ore deposits were discovered by a pair of farmers in 1610. Soon, a mint was established there, along with the mining town of Ashio which flourished throughout the Edo period. The copper was used to construct the famous Nikkō Tōshōgū Shrine, as well as Zōjō-ji Temple in Edo (Tokyo), and for the minting of the Kan’ei Tsūhō coins. The mines are said to have produced a great amount of copper, sometimes even 1,500 tons a year.

The Ashio Copper Mine became privately-managed in 1871. By then, only about 150 tons of copper were quarried yearly. Furukawa Ichibei, who became the owner in 1877, discovered several new veins of copper thanks to the introduction of advanced mining technology. However, this also led to its downfall as the excessive deforestation, emission of toxic smoke, and discharge of industrial wastewater caused serious problems to the surrounding region. 

The incident led to the birth of the environmental movement in Japan, but it was not until 1974, one year after the closing of the mines, that the Furukawa Co, Ltd. was held accountable for the poisonings. 

Pollution issues are not the only part of the mountain’s dark history. In 1907, miners rioted for three days demanding better treatment, and a large portion of the mining facilities were destroyed by fire.

During World War II, the Ashio Copper Mine made use of POW slave labor mainly consisting of Korean prisoners. Chinese POWs were also forced to work in the mines and more than 100 were killed. These victims of wartime atrocities are commemorated and are honored by several cenotaphs built near the mountain.

Although the Ashio Copper Mine’s pollution problems are infamous across Japan, its historical significance and current status as a tourist attraction are not as well-known. After its closure, the mine was opened to the public in 1980. Visitors can ride a train through the old mine and discover its history at the adjacent museum.