Coloured blackboard chalk based on calcium sulphate. Suitable for all board surfaces for writing and designing. 12 colours, dust and toxin-free, 13 x 85 mm, convex. Mercurius is a subsidiary of Neuguss Verwaltungsgesellschaft, Berlin. Mercurius is one of the leading Waldorf school and Waldorf kindergarten outfitters. Mercurius Stockmar sells products and products from specialist suppliers of high quality teaching materials to (Waldorf) schools worldwide. The company with many years of experience offers a uniform core assortment worldwide in high quality, with product safety and at fair prices. It produces socially and responsibly. High social and environmental standards are maintained and there is cooperation with social therapy workshops.