Spiegeleisen

Spiegeleisen, a variety of cast-iron which contains a very high percentage of carbon, sometimes 5 per cent. It also always contains manganese to the extent of 5 per cent., and frequently much more. Owing to this constituent, it is much used for the production of steel by the Bessemer process, as, although but little of the manganese passes into the steel, yet it materially improves the quality of the product.