manganese

Etymology

From French manganèse, from Italian manganese, by alteration from Latin magnesia (“magnesia”), from Ancient Greek μαγνησία (magnēsía), after Μαγνησία (Magnēsía, “Magnesia”). Doublet of Magnesia, magnesia, and magnesium; more at magnet.

noun

1. (uncountable) A metallic chemical element (symbol Mn) with an atomic number of 25, not a free element in nature but often found in minerals in combination with iron, and useful in industrial alloy production.
   Oxygen levels on Earth skyrocketed 2.4 billion years ago, when cyanobacteria evolved photosynthesis:[…]. The evolutionary precursor of photosynthesis is still under debate, and a new study sheds light. The critical component of the photosynthetic system is the “water-oxidizing complex”, made up of manganese atoms and a calcium atom. 2013 September-October, Katie L. Burke, “In the News”, in American Scientist
2. (countable) A single atom of this element.