The Saru River History Museum is currently holding a special exhibition titled “Nibutani’s Famous Stones and Aotora-ishi.
Aotora Stone is a stone produced only in the Nukabira River in the Saru River system, and is popular as a garden stone and a viewing stone because of its distinctive blue-green stripe pattern.
It was also used as a stone axe in the Jomon period, and has been excavated at the Sannai-Maruyama site in Aomori Prefecture, a World Heritage Site in the Northeastern Jomon group of Hokkaido.

 

Aotora Stone (ornamental stone).

Aotora Stone and Hidaka jade guardian sword.

The oddly named “Koutaro-ishi” (Kotaro stone).

View of Lake Nibutani in late autumn from the History Museum.

Nibutani Dam monument of “Hidaka ao-ishi(Hidaka blue stone)”.