The Nirayama Reverberatory in Izunokuni City is an iron smelting furnace built in the late Edo period. The furnace had to be resistant to extreme temperature as high as 1800C degree in order to melt impure iron. Local white clay from Nashimoto area in Amagi Mountain was chosen for bricks' base material. Because of its fire retardant quality, the local people had traditionally been using the white clay to build their cooking ovens. The main material of white clay is metamorphic rock. Having been transformed by volcanic activities, it had been known for its high heat tolerance. Using this white clay as the base material, high quality Japan-made bricks were created. The bricks were baked in Kawazu area in Izu, and then delivered by boat through Suruga Bay, Numazu area and then up streamed along Kano River before reaching Nirayama where the furnace was located. The furnace still exists and visitors can see the structure.