A black or dark grey mineral with a metallic lustre, consisting of manganese dioxide.
- ‘It never occurs as a free element, but only in ores such as pyrolusite, manganite, psilomelane, and rhodochrosite.’
- ‘Acicular crystals and crystal aggregates of pyrolusite are found in vugs in the pegmatites of the district.’
- ‘The ore, a mixture of ‘psilomelane’ and pyrolusite with much manganiferous limonite, contains masses of cerussite.’
- ‘Scheele produced chlorine by treating the mineral pyrolusite with hydrochloric acid (HCl).’
Early 19th century: from pyro- ‘fire, heat’ + Greek lousis ‘washing’ (because of the mineral's use in decolorizing glass).
We take a look at several popular, though confusing, punctuation marks.