Izu Roppongi Stone (Shizuoka Prefecture) [Famous Japanese Stones]

IZU Hexagonal stone

Izu Hexagonal Stone

Lava from the Pliocene epoch (approximately 5 million to 2.58 million years ago), when the Earth was cooling rapidly.
After this, a long ice age continued until 10,000 years ago, causing mass extinction of species.
It is an intrusive rock made of amphibole dacite, formed when lava solidified underground and formed pentagonal to hexagonal columnar joints that emerged from the ground (columnar joints).
Most are about 10 to 20 cm thick, and when mined are a light blue color, but because they contain iron, they rust and turn reddish over time.
Because of its unusual shape, it has been loved for a long time, with people simply placing it in their gardens as an object of art.
Currently, Izu Roppongi is no longer mined and is difficult to obtain.
In Japan, the same structure can be seen in Genbudo Cave in Hyogo Prefecture and Sasebo in Nagasaki Prefecture.

This is lava from the Pliocene era (approximately 5 to 2.58 million years ago), when the Earth was cooling down. After this, the ice age continued for a long time until 10,000 years ago, and a mass extinction of creatures occurred. It is an intrusive rock of amphibole dacite that has grown from the ground as lava that hardened underground and jointed into pentagonal or hexagonal pillar shapes (columnar joints). Most of them are about 10 to 20 cm thick, and when they are mined, they are slightly light blue, but because they contain iron, they rust and turn reddish over time. Because it has such a mysterious shape, it has been loved for a long time and has been used as an object in gardens. Currently, IZU Hexagonal stone is not mined and is difficult to obtain. In Japan, same structures can be seen in Genbudo Cave in Hyogo Prefecture and Sasebo in Nagano Prefecture.