A calciferous sandstone natural whetstone from Kyushu Island, Japan. Ideal for sharpening dull but undamaged edges it readily releases dulled abrasive particles meaning it can be rinsed for rapid sharpening, or a slurry allowed to build up for a finer finish. The particles are rated between 800-1000 grit on the Japanese scale, but will produce a finer finish with shallower scratches than similarly rated synthetic stones. Use with water, and store, or soak in water for 10 minutes before use. Approximately 150mm by 45mm by 20mm.