 The manganese content of the Dannemora ore caused impurities, which would otherwise have remained in the iron, to react preferentially with the manganese and to be carried off into the slag.This level of purity meant that the iron was particularly suitable for conversion to steel by being re-carburized, using the cementation process.This made it particularly suitable for making steel, oregrounds iron was an indispensable raw material for metal manufactures, particularly the Sheffield cutlery industry.