The stone is split before it is polished. What is quarried at Ogatsu is a hard black slate with an unusually even grain, and it takes a deep gloss when worked. Making an inkstone begins by splitting that stone along its bedding planes, and the surface the split produces is kept and worked with rather than cut away, so the material decides a good deal of the finished shape before the maker touches it.

Inkstone quarrying here is recorded from around 1396, which makes this a producing district of more than six hundred years. At the local heritage hall the raw stone is displayed alongside the tools, splitting tools and polishing tools together, and the difference between the two sets is the whole of the craft. Ogatsu received prefectural recognition in December 1982 and national designation from the minister in May 1985, by which time the craft had been running here for around six centuries without it. This is a small coastal settlement with very few shops, about forty minutes from central Ishinomaki by car, and the quarrying and the making have always happened within sight of each other.

An inkstone is nothing but its grinding surface. If the grain is too fine the ink will not come off the stick; if it is too coarse the particles come away unevenly and the ink is gritty — so the places where stone of exactly the right hardness and grain can be quarried became, without further argument, the places where inkstones are made. There is no second-best site available, and no way to make an ordinary stone behave like this one. This district has not moved in six hundred years for the simplest possible reason: the stone cannot be moved either.