• Mt. Apoi Peridotite Plaza

Mt. Apoi Peridotite Plaza

The Peridotite Plaza, an outdoor museum of large polished stones including peridotite and other rock specimens from the Hidaka Mountains, is displayed in front of Samani Town Hall.
The stones are packed with scientific information and have been cut and polished into different shapes.
Pamphlets are available in the east part of the plaza. On a clear day, the plaza offers an amazing view of Mt. Apoi.

Rock Specimens



Also, look for the garnet stones, a light red-colored mineral produced deep with the earth. The garnets are about 1 cm in size.

Volcanic Eruptions and Peridotite

Japan is one of the world's most volcanic countries with 110 volcanoes that make up 7% of the earth's active volcanoes. Many of you have probably seen videos of volcanic eruptions with lava, but where do you think the lava comes from?
When lava is below ground it is called magma, and the source of magma comes from the mantle, tens of kilometers below the surface of the earth. The mantle is also where peridotite rock originates. Many people might think that the mantle deep below the earth consists of molten rock and magma, but it is actually made of solid rock.
For that reason, places where the mantle appears above ground in its current state, like Mt. Apoi, are extremely valuable. Since it is believed that peridotite is the source of lava (magma), it is essential to study the peridotite of Mt. Apoi in order to understand volcanic eruptions.


Different types of peridotite

Four types of peridotite, telling us about events in the Earth's interior
Four types of Horoman peridotite contain different proportions of minerals. These are extremely valuable scientific specimens for research on the formation and rising movement of the magma in the Earth's interior.