Ohya Museum

The museum is an underground museum that was built on the site of an Oya Stone quarry. Even if you are not familiar with the name Oyaishi, the texture of the stone should be familiar to you.

This stone has long been used as a building material for houses and walls, but where and how it is mined is a valuable experience that can only be seen here.

In the museum, there is an exhibit that shows the history of Oyaishi mining. Materials from the mid-Edo period to around 1959 are on display, including tools from the hand-drilling era, mining methods, and changes in transportation.

The highlight of the museum is the underground mining site. It is a huge space covering an area of 20,000 square meters, and is 30 meters deep, reaching 60 meters underground at its deepest point.

The average temperature inside the mine is usually around 8 degrees Celsius. There are approximately 10 million quarried stones, and it is truly like a huge underground structure.

In this fantastic underground space, concerts, plays, shows, Noh plays, weddings, and other events are held. It is also used for filming movies and dramas.

The ruins of the Oya Stone quarry and the surrounding greenery blend harmoniously to create a unique landscape.

The main exhibits are as follows

Geology of Oya
Mining method and form of Oyaishi
Ruins of Oya Stone Underground Mining Site (huge underground space)
Transition of stone removal and transportation

Furthermore, in addition to the general exhibits, cultural events such as concerts, sarugaku performances, movie nights, theater performances, art exhibitions, dance performances, and seminars are held.

In addition, movies, TV dramas, TV commercials, and promotional videos are filmed here.

Every year, the site is also used as the venue for festivals at Oya, and events such as projection mapping are held in the underground space.

Regarding the history of Oyaishi and the underground mining site, Oyaishi was used as material for sarcophagi during the Kofun period (burial mounds), and in the 8th century, Oyaishi was used in the construction of Shimono-kokubunji and Shimono-kokubuninji temples.

In addition, the Otani Temple in Utsunomiya City has a Buddhist image of a Buddha made in the Heian period (794-1185), and its principal image, the Thousand-Armed Avalokitesvara, was carved from Otani stone.

Oyaishi is a pumice tuff stone mined in the Oya-cho area northwest of Utsunomiya City. Because of its flexibility and ease of processing, it has long been widely used as a building material for exterior walls and storehouses. Even today, it is used for the walls of warehouses.

The matrix of Oyaishi is mainly composed of float glass, plagioclase, and quartz, with a small amount of biotite hornblende pyroxene. It also contains silicic acid, ferric oxide, aluminum oxide, manganese oxide, lime, magnesium oxide, potassium, and sodium.

Oyaishi is thought to have been formed in the first half of the Cenozoic Tertiary Miocene Era, when the Japanese Islands were still underwater. Volcanic ash and sand and gravel erupted from volcanoes and precipitated into seawater, which solidified to form Oyaishi.

In the vicinity of Oya Town, the distribution of Oyaishi extends 4 kilometers from east to west and 6 kilometers from north to south. There are 12 quarries as of 2009, with an annual shipment of about 20,000 tons, and estimated reserves of about 600 million tons.

While open-pit mining is used in some areas, most of the quarries are dug underground at depths ranging from several tens of meters to more than 100 meters. At its peak in the 1960s, there were about 120 quarries active.

Many stones similar to Oyaishi are distributed in Tochigi Prefecture and are called Nagaokaishi, Fukaiwaishi, Iwafuneishi, Motegiishi, etc., after their respective places of origin.

Oyaishi is light and soft, making it easy to process, and has excellent fire resistance and moisture proofing properties. As a result, Oyaishi is used in a wide variety of applications, such as for fire escapes, stone walls, firewalls, gateposts, and paving stones.

It is also used as a structural material for bread and pizza ovens and stone cauldrons due to its high fire resistance and heat storage capacity. In the field of rock engineering, it is also used for experimental samples as an easy-to-handle material.

In the production area around Utsunomiya, it has been confirmed that Oyaishi was used as furnace stone in pit buildings during the Jomon period. Oyaishi is widely used for the exterior walls of stone warehouses and other buildings, railroad station platforms, stone walls, stairs, and gateposts.

The gyoza (dumpling) statue installed at Utsunomiya Station in conjunction with a TV program and the Utsunomiya Catholic Church (commonly known as the Catholic Matsugamine Church), built in 1932, are also constructed of Oyaishi. Oyaishi has also long been used in the construction of local historical buildings such as Shimono-Kokubunji Temple and Utsunomiya Castle. The unique texture of Oyaishi became widely known when American architect Frank Lloyd Wright used it in the former main building of the Imperial Hotel in Tokyo.

Immediately after it is quarried%2