[7] It is a black, amorphous appearing mineral, often with a granular, fibrous, or columnar structure, sometimes forming reniform crusts.

Pyrolusite occurs associated with manganite, hollandite, hausmannite, braunite, cryptomelane, chalcophanite, goethite, and hematite under oxidizing conditions in hydrothermal deposits.

Black, manganese oxides with a dendritic crystal habit often found on fracture or rock surfaces are often assumed to be pyrolusite although careful analyses of numerous examples of these dendrites has shown that none of them are, in fact, pyrolusite.

[8][9] Some of the most famous early cave paintings in Europe were executed by means of manganese dioxide.

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.

[10] Manganese dioxide, in the form of umber, was one of the earliest natural substances used by human ancestors.

[11] 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.