Shakudani stone

What Shakudani stone is

Shakudani stone, shakudani-ishi, is a volcanic tuff quarried from the Asuwa Hills in the centre of Fukui City. It is also called Echizen stone or Fukui stone, and because it turns a deeper blue when wet it is sometimes known as Echizen blue stone. According to the Geological Survey of Japan, it is a Miocene tuff, and quarrying goes back to the Kofun period.

Soft and easy to work, it served many purposes. It was used for stone coffins in ancient tombs, for Buddhist figures and memorial towers in the medieval period, and for castle walls and roof tiles in the early modern period; the keep of Maruoka Castle is well known for its roof of Shakudani stone tiles. From the port of Mikuni it was shipped along the Sea of Japan coast by the kitamaebune coastal traders, and objects made of it survive as far away as Tohoku and Hokkaido.

The stone was mined underground. The same source states that the last quarrying business closed in 1999, and no new stone is extracted today, which makes matching replacement stone for repairs difficult.

Reading the records and the stone

Records note where the stone is used. The gate of the Saito family house has main and bracing posts of Shakudani stone, the main posts 3.1 metres tall, and the record calls it one of the largest stone gateposts of its kind in the prefecture. The front gate of the Tengurō restaurant has a ridge stone and end ornament carved from it, and the restaurant building uses it to pave the entrance. The stone storehouse of Aizanso is built of courses of Shakudani stone. Gateposts, ridge ornaments, paving and walls all draw on the same material.

On site, look at the colour and texture. A fine-grained, blue-green grey stone whose surface has weathered to soft, rounded edges may well be Shakudani stone, and the blue shows more strongly after rain. Other tuffs of similar colour occur around Fukui, however, and the record is the reliable basis for identifying the source.