Ogatsu stone

Ogatsu stone names black slate produced in Ogatsu-cho, Ishinomaki City, and stone material made from that slate. The boundary is concrete: a place in Miyagi, a black hard slate, and objects cut from it. Ogatsu inkstones use Ogatsu stone as the required material, so the craft of the inkstone and the quarrying of the slate meet in the same district. The Ogatsu Suzuri Production and Sales Cooperative is based around the Ogatsu Suzuri Traditional Industry Hall area, tying the material to workshops, quarry work, and the people in Ogatsu-cho who cut, carve, and finish the stone.

Ogatsu stone belongs to Paleozoic Permian black hard slate. Its surface is pure black, its grains are described as even, and the stone is strong under compression and bending. It absorbs little water and resists chemical action and long-term change. A stable inkstone surface, a roof slate exposed to rain, and a thin stone plate all depend on those material traits. The stone also carries natural surface patterns; after smoothing, carving, lacquer gloss, firing, or ink-blackening, the black surface can hold depth and sheen without leaving the material world of slate.

The making of an Ogatsu inkstone starts with quarrying. After stone is taken from an open quarry, selected pieces without stone flaws, cracks, or split lines are cut according to the intended size, thickness, and shape of the inkstone. The cut stone is placed on a rotating disk grinder while river sand and water pass across the surface, wearing down irregularities until the stone becomes smooth. Chisel work follows in three stages: edge-setting, rough carving, and finish carving, using tools such as hori-nomi, komaru-nomi, and kuri-nomi. Polishing is also staged with whetstones and waterproof paper, and the final surface may be brought out with lacquer gloss, firing, or ink-blackening.

The use of Ogatsu stone for inkstones reaches back about six centuries to the Muromachi-period timeframe. Local oral accounts say that during the Genna years, when Date Masamune traveled to the Tashima and Oshika Peninsula area for deer hunting, two Ogatsu inkstones were presented to him; the second lord Tadamune is also said to have valued the skill of inkstone makers, with mountains yielding inkstone material called otome-yama and restricted from ordinary quarrying. These accounts place the black slate in a concrete writing setting: stone cut from Ogatsu, shaped into an inkstone, and set beside ink, water, and brush.

Ogatsu stone also moved beyond the inkstone bench. In the Meiji and Taisho periods, Ogatsu slate was used as roofing material on Japanese- and Western-style buildings, with Tokyo Station named among the examples. Thin, hard, low-absorption slate made sense on a roof where rain and time test a surface. Meiji-era education also increased demand for writing tools: Ogatsu stone was made into inkstones and slate writing boards for schoolchildren, carrying the same black material from brush practice into classrooms and buildings.

Recent Ogatsu stone work uses the raw material's ability to split thinly, shaping it into stone plates and other objects beyond inkstones. The black surface gives cups, table objects, and small daily items a clear outline, while the use still depends on strength, low water absorption, and the way slate separates into thin layers. From the late Showa period onward, Ogatsu stone was also made into dishes, coasters, clocks, and varied craft goods. The move from inkstone to stone plate keeps the same black slate from Ogatsu-cho while placing it on a dining table, in a room, or beside a clock face.

After the 2011 Great East Japan Earthquake and tsunami, Ogatsu-cho suffered severe damage to the Ogatsu stone industry, fisheries, and tourism; its resident population fell from about 4,200 before the disaster to about 1,000. The problem for Ogatsu stone therefore sat in quarries, workshops, employment, and dispersed residents as much as in the material itself. From April 2012, the Ogatsu Ishinowa Project worked with the inkstone cooperative and local administration around natural slate and Ogatsu inkstones, focusing on places to gather, object-making, and people development. A separate long-term challenge remains succession, because quarrying and inkstone making lack enough successors.