Besshi Copper Mines Heritage of Industrial Modernization

An outcrop is a mass of mineral deposits breaching the Earth’s surface and extending underground. Several outcrops are visible around Besshi. The Great Outcrop near the highest point of the Besshi Copper Mines is the very tip of the Besshi copper deposit and is a rocky mass more than 2 meters in length. Its reddish-black color indicates the high quality of the copper deposit.

The Besshi Copper Mines are located a little to the south of the Median Tectonic Line (MTL), Japan’s longest geological fault, which runs from Kanto to Kyushu. The geological features to the north of the MTL are quite different from those to the south of it and the MTL fault zone was formed by the collision between northern and southern strata about 100 million years ago. The energy generated by this collision resulted in large-scale volcanic activity underground and the heat of the magma led to formation of the Besshi mineral deposit. This is a bedded cupriferous iron sulfide deposit (Kieslager-type deposit). Referring to its characteristic form, deposits of this type are widely known as Besshi-type deposits worldwide. The strata around the Great Outcrop are all inclined, indicating that a major tectonic deformation occurred here.

In 1690, Tamuki Jyuemon, who was a clerk of the Yoshioka Copper Mine (Takahashi City, Okayama Prefecture) run by Sumitomo, heard of a promising mineral vein in the mountains of Shikoku. A delegation led by Tamuki Jyuemon sailed crossed the Seto Inland Sea, traversed the Kobako Pass in the steep Akaishi mountain range that rises to more than 1,200 meters above sea level, and arrived at Otoji in Besshiyama Village. Then, they followed the Dozan River to its source, made their way through dense forests, and finally came upon the outcrop exposed at the surface. This is where, at an altitude of 1,210 meters, the Kanki Shaft was eventually excavated. Tradition has it that the shaft was named “Kanki (meaning “joy” in Japanese)” because Tamuki Jyuemon and his companions were so delighted with the discovery of the deposit that they hugged one another with joy.

The Kanto Shaft was excavated right next to the Kanki Shaft. These two shafts served as the main shafts of the Besshi Copper Mines for 200 years until the early years of the Meiji era and the ore discharged from these shafts was smelted at smelting stations known as a “fukisho” or “tokoya” located at a somewhat lower level on the mountainside overlooking the valley.

Different from the arch-shaped entrances introduced in the Meiji era, the entrances of these shafts were made using the “yotsudome” method that involved assembling logs into a square shape braced with wooden panels to prevent collapse of the overburden. Small shrines were placed on pillars at the entrance and workers prayed for safety underground. The Kanki Shaft and the Kanto Shaft exist to this day, having been repaired and restored in 2001.

Only a few meters from the Great Outcrop is the entrance to the Yamato Shaft, the shaft at the highest altitude in the Besshi Copper Mines. Opened in 1691, it is the third oldest shaft, following the Kanki Shaft and the Kanto Shaft, and it essentially retains its original condition.

Although one cannot enter the shaft now, it leads to the northern slope of the mountain. To the north of the watershed in Tatsukawayama Village, formerly in the Saijo Domain, are remains of the Tatsukawa Copper Mine, which is thought to have been developed by the people of that village during the Kanei period (from 1624 to 1643).

In fact, the same mineral veins run through the Tatsukawa Copper Mine and the Besshi Copper Mines, being were mined from the north and the south. It often happened that the miners from the respective mines, extending their galleries from opposite directions, would break through the rock separating them, resulting in underground encounters that led to major disputes over mining rights.

The mining conditions of the Tatsukawa Copper Mine on the northern slope were less favorable and management of the mine gradually deteriorated. Osakaya, the owner of the Tatsukawa Copper Mine, approached Sumitomo in around 1747 and proposed the sale of the mine to Sumitomo. After several attempts to negotiate a deal, the two families reached an agreement and from 1764 onward the House of Sumitomo was in charge of both the Besshi Copper Mines and the Tatsukawa Copper Mine.

There were many temples and shrines at the Besshi Copper Mines. Shinto gods, including those derived from the Kompira, Inari, and Gion shrines, were worshiped. In the Buddhist tradition, there was also a Kannon-do temple to pray for souls in the afterlife and a Jizo-do temple where Jizo Bosatsu was enshrined. Among the Shinto shrines, the largest was the Oyamazumi Shrine, home of the tutelary deity of mines worshiped by the inhabitants of the mining town. The photos show the Oyamazumi Shrine as it used to be and the present condition of the site.

The Oyamazumi Shrine is home to the tutelary deity who guards the Besshi Copper Mines. Derived from the Oyamazumi Shrine on the island of Omishima off the coast near Imabari when the mines were inaugurated in 1691, the god was enshrined in Ashitani in Besshiyama Village. Oyamatsumi, the principal deity of the Oyamazumi Shrine, is the god of mountains, sea, and war.

In the spring of 1694, a fire broke out at an oven near the office of a government official. Because of a drought, the fire swiftly engulfed the parched trees and scrub, spreading rapidly. All the facilities were burnt down except eight “tokoya” refineries and 132 people perished.

To rebuild the mining town, Sumitomo also rebuilt the Oyamazumi Shrine and prayed for protection of the operation of the mines. At first, the shrine was located on a hill (Enginohana) with a good view of the entire mining town and remained there until 1892, keeping a watchful eye on the prosperity of the mines. Small shrines were placed at the entrances of shafts and miners never neglected to bow respectfully before entering the shafts.

Subsequently, the Oyamazumi Shrine was relocated in line with the movement of the center of the mining operations. Following the relocation to Mettamachi in 1892, the Oyamazumi Shrine was relocated to Tonaru in line with the relocation of the Mine Headquarters in 1915, and to Kawaguchishinden (present-day Yamane) at the foot of the mountain in 1928. Even since the closure of the mines, Sumitomo Group companies hold rituals at the New Year and in the spring on May 9 every year.