The mine is located at an altitude of 900 meters on the hillside of Mt. Hachimantai in the northwestern part of the prefecture.
Its ore deposit consisting of four ore bodies had a diameter of 1,500 meters with a maximum thickness of 150 meters, which was referred to as the largest in the East.
Washichi Sasaki, a local villager, discovered an outcrop in 1882 and applied for an exploration permit together with his elder brother Wasuke six years later.
Subsequently, mining rights were transferred several times, and the mine was operated on a small scale under the name of Yoriki Sulfur Mine and later Iwate Sulfur Mine in the early 20th century.
Masuda General Partnership, a trading company in Yokohama, acquired the rights in 1913 and identified rich sulfur reserves through mineral exploration.
Thereupon, the company established Matsuo Mining Co., Ltd. the following year and initiated a large-scale mine devlopment.
The mine increased its production due to a rise in demand for sulfur with the development of the chemical industry, and its output held the first place in the country from 1922.
The company began iron sulfide ore mining in 1921 and sold its concentrate to sulfuric acid plants.
Additionally, the company developed overseas sales channels in the first half of the 20th century.
As a result, products were exported, namely, refined sulphur from Yokohama Port to Australia and New Zealand, and iron sulfide ore from Hachinohe Port to the then colonized Manchuria and Korea.
Under such circumstances, production decreased from 1941 due to a cave-in accident killing 82 miners in 1939, successive fires, air raids, and a labor shortage.
After the war, production multiplied owing to industrial policies, the special procurement demand during the Korean War, and the development of the chemical industry.
The rapidly grown mine produced over one million tonnes of crude ore, 635,936 tonnes of iron sulfide ore, and 79,499 tonnes of refined sulfur in 1956.
Around the same time, the demand for sulfur products declined from the effects of a downturn in the chemical fiber industry, and furthermore, the distribution of sulfur recovered from petroleum refining exacerbated the decline later.
In 1966 and 1967, the mine produced over one million tonnes of crude ore again, reaching its peak.
However, the mine was closed due to overproduction, trade liberalization, and the spread of recovered sulfur.
The remains of apartment houses built in 1951 can be seen even now.
Motoyama area was developed into a production base, and numerous mining facilities, such as beneficiation plants, refineries, and ore storage facilities, were built beside the opencast mining sites.
Four aerial cableways, each with a length of 3.6 kilometers, run in parallel and connected Motoyama to Yashikidai, located at the base of the mine, transporting products, production materials, and daily necessities.
Yashikidai area was developed into a shipment base, and an exclusive railway line was laid to connect Obuke Station on the JNR Hanawa Line with a distance of 12.2 kilometers.
The railway line also began operations for carriage of passengers as a local line from 1948.
The number of employees totaled 4,897 in 1952, and mining towns at Motoyama and Yashikidai had a total population of 15,000.
Motoyama, located on the heights, had 11 apartment houses made of reinforced concrete, 390 row houses, an elementary school, a junior high school, a part-time high school, a hospital, a post office, a theater, and others.
Its appearance like a mining city was praised as a "Paradise above the Clouds".
元山地区 Motoyama area
屋敷台地区 Yashikidai area
The Remains Photographed in Abandoned Matsuo Mine
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松尾鉱業の創設以降、およそ 2,900 万 t の鉱石が採掘され、1,000 万 t の硫酸原料と 210 万 t の硫黄が生産されました。坑道の標高差は 245 m に及び、総延長は 255 km に達します。
The mine produced 29 million tonnes of ore, 10 million tonnes of raw material for sulfuric acid, and 2.1 million tonnes of sulfur after the foundation of Matsuo Mining Co., Ltd.
The mine tunnels have a difference of elevation of 245 meters and a total length of 255 kilometers.
Midorigaoka Apartment Houses were built with reinforced concrete in 1951 and were provided with modern conveniences, such as a steam heating system and flushing toilets.
They became a symbol of prosperity of the mining city, which was praised as a "Paradise above the Clouds".
A large amount of highly acidic drainage flowed into the Akagawa River, flowing near the mine, and contaminated the main stream of the Kitakami River.
After the closure of the mine, the nation and the prefecture built a neutralization treatment facility, and its operation has been continuing.