Pigment, Glass and the Tangled Name

Manganese compounds have served human craft since prehistory: manganese dioxide gave the deep blacks and browns of Palaeolithic cave paintings, and the same substance, called glassmakers' soap, was added to molten glass from Roman times to cancel the green tint of iron and produce clear glass, or in excess to colour it purple. The element's name is entangled with magnesium and magnet through their common origin in the mineral wealth of Magnesia, a confusion early chemists worked to separate. Manganese has no planetary or alchemical station of its own, but as a pigment and a glassmaker's reagent its ores were worked and valued long before the metal was named.

Archaeologists have recovered manganese oxide crayons, shaped and worn from use, at Palaeolithic sites including those near Lascaux, direct physical evidence that prehistoric artists deliberately sought out and prepared the mineral for its pigment. Pliny the Elder described the glass-clarifying property of manganese ore in the first century, a practical knowledge that long predated any understanding of why it worked. The element also has a harsher occupational history: miners and smelters exposed for years to manganese dust can develop manganism, a Parkinson's-like neurological disorder first clinically described in 1837 by James Couper among Scottish workers grinding manganese ore at a Glasgow bleach works, with the much cited Chilean cases following more than a century later.