Pyrolusite is a mineral consisting essentially of manganese dioxide (MnO<sub>2</sub>) and is important as an ore of manganese. It is a black, amorphous appearing mineral, often with a granular, fibrous, or columnar structure, sometimes forming reniform crusts. It has a metallic luster, a black or bluish-black streak, and readily soils the fingers. The specific gravity is about 4.8. Its name is from the Greek for fire and to wash, in reference to its use as a way to remove tints from glass.
History
Some of the most famous early cave paintings in Europe were executed by means of manganese dioxide. Blocks of pyrolusite are found often at Neanderthal sites. It may have been kept as a pigment for cave paintings, but it has also been suggested that it was powdered and mixed with tinder fungus for lighting fires. Manganese dioxide, in the form of umber, was one of the earliest natural substances used by human ancestors. It was used as a pigment at least from the Middle Paleolithic. It may have been also used by the Neanderthals in fire-making.
The ancient Greeks had a term μάγνης or Μάγνης λίθος ("Magnes lithos") meaning stone of the area called Μαγνησία (Magnesia), referring to Magnesia in Thessaly or to areas in Asia Minor with that name. Two minerals are called μάγνης, namely lodestone and pyrolusite (manganese dioxide).(not to be confused with the current mineral called Lodestone, which does not contain Manganese. Lodestone is a naturally magnetized form of the iron mineral Magnetite. FeFe2O4)
The term μαγνησία was used for manganese dioxide. In the sixteenth century it was called "manganesum". It also was called Alabandicus (from the Alabanda region of Asia Minor) and Braunstein. Eventually the name of the element manganese was derived from "manganesum", whereas "magnesia" came to mean the oxide of a different element, magnesium.
See also
Other manganese oxides:
- Birnessite
- Psilomelane