It is widely distributed in Japan, and its decomposed products are excellent raw materials for porcelain. The causes of its decomposition are not fully clear, but for example, Hanasakaishi and Gokokujiishi for Kutani ware, Izushiishi, Kakitaniishi, and Tobiyaishi for Izushi ware are kaolin from weathering of quartz coarse-hedged rock, Izumiyamaishi for Arita ware is residual clay from quartz coarse-hedged rock from sulfuric action, and Okubo-ishi and gravel soil for Aizu ware are residual clay from quartz coarse-hedged rock from hot spring action. Amakusa stone is quartz coarse-grained clay. Amakusa stone is a semi-decomposed product of quartz coarse-grained rock, and is the whitest porcelain material in Japan.
