Kurama Stone (Kyoto)

Kurama stone (Kurama-ishi) is a natural igneous rock from the Kurama area of Sakyo Ward, Kyoto: a Cretaceous quartz diorite whose main facies is hornblende–biotite tonalite, rich in the iron sulfide pyrrhotite. As the pyrrhotite oxidizes, the stone takes on a characteristic rust-brown color, and it has long been prized as a high-grade garden stone for tea gardens. Although sometimes sold as granite, it is a quartz diorite (a granitoid rock), not granite in the strict sense.