The Omi River Basin, formed by plate subduction hundreds of millions of years ago, contains large amounts of jade, crystalline schist, serpentine, and other rare minerals usually only found deep within the earth. Beautifully colored jade, contrasting striations on metamorphic rock, and newly discovered minerals such as ohmalite, nunakawaite, and itoigawaite illustrate the romance and mystery of the subterranean world below us. Thanks to the unusual topography of this region, we can easily observe and touch these rare minerals usually hidden deep underground.

Even though the Jade Gorge has been designated and preserved as a National Natural Treasure, it has not avoided damage inflicted by careless jade thieves. Deposits which have been unfortunately damaged by illegal digging have been removed to the Jade Village Center at Oyashirazu Pier Park and the Omi Museum of Natural History for preservation.

If you climb the slope up Kanayama Valley, you can find deposits of Ohmilite and Nunakawaite encased in deposits of albitite, a very rare rock found nowhere else in Japan. Also, in the Omi River, flecks of gold still can occasionally be found from the now abandoned Hashidate Gold Mine located upstream.