Clay mined from the bottom of rice fields. It is excavated from clay layers deposited at the bottom of valleys after the clay from the hills has weathered and been washed away by rainwater. It is characterized by its fine texture and high iron content, and is used to make colored stoneware with a smooth skin. The raw material for rough stoneware is the un-watered material as it is dug out. Clay from rice fields in Tokoname, Tokoname City, Aichi Prefecture, and adjacent valleys such as Itayama (Handa City), Sakai (Tokoname City), Uenoma, and Kawawa (Mihama Town, Chita County) has been mined since the mid-Muromachi period. The same is true of Bizen. In the “Chawaniki Bengokushu” (Tea Utensils Bengokushu), the article on Seto tea containers, which describes the soil as “rice field soil, white in color.
