The history of production of gold and silver in Sado goes back to the ancient times. It is said that it was at Nishimikawa Placer Gold Mine that panning gold was conducted, which appears on Konjaku-monogatari-shu, Tales of Times Now and Past, edited around the end of the 12th century.
At Nishimikawa Placer Gold Mine, after dirt containing gold into a stratum was dropped down into the waterways, miners would flush out all of the water at once in a process known as “Onagashi” to wash down any excess dirt. In this case, there was a shortage of water required. Therefore, long waterways coming from a water source were erected, and reservoirs were made so that a large amount of water could be stored. Here, remains of gold panning and these waterways still survive, widely distributed.
It is estimated that placer mining has been conducted at this gold deposits since the end of the Heian period (the end of the 12th century). Mt. Toramaruyama is the largest mining site in Nishimikawa Placer Gold Mine. Even today, the mountain slope whose soil used to be scraped for gathering gold still never allow any plants to grow, with its red colored surface exposed.
Piled-up stone structure (Workshop, Rest area)