Hydration by Chemical Weathering
Chemical Process (Alteration) - Ground surface (Meteoric)
Required Geological Setting
Occurrence
Hydrate minerals formed by chemical weathering under the humid circumstances on the surface of the earth. Na and K in minerals are dissolved and replaced by OH or H2O. Vermiculite is formed from mica group minerals. Allophane, Halloysite and montmorillonite are formed from feldspars.

Distribution of hydrate minerals by chemical weathering in this site.
Mineral Assemblages
Vermiculite, Allophane, Halloysite, Montmorillonite
Localities
- Tano (Vermiculite)
- Ono (Vermiculite)