Definition of "pyrolusite" []

• A soft, black to dark gray mineral, MnO2, the commonest and most important secondary ore of manganese. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "The heat and carbon in the charcoal separated oxygen from the pyrolusite, leaving a metallic manganese residue."
• "The most important mineral is pyrolusite, because it is the main ore mineral for manganese."
• "In 1774, while heating the mineral pyrolusite (MnO2, manganese dioxide) in a charcoal fire, the Swedish scientist Johann Gahn discovered manganese."