Dannemora iron mines, Sweden, c 1856.

Coloured lithograph by E M Baerentzen after an original drawn by A Mayer. The Dannemora mines have been producing iron ore since the 15th century. The mines are a series of around 40 deep, steep-sided quarries. The ore has a very high percentage of metal within it, sometimes as much as 90%, which enables iron and steel of very high quality to be produced from it.