pyrolusite

Pyrolusite is an oxide of manganese that usually occurs as powdery masses or crusts, often in combination with other manganese-bearing oxide minerals such as chalcophanite, coronadite, romanèchite etc., with which it is readily confused. Such accumulations would seldom have been prioritised for specimen retention while less conspicuous occurrences would be readily overlooked.

Geier (1973/1974) noted the presence of manganese oxide coatings in the second oxidation zone which he interpreted as mixtures of pyrolusite, psilomelane and coronadite.

Bartelke (1976) described pyrolusite as occurring "… in powder form or in radial crystalline masses".

Pinch and Wilson (1977) stated that "Powdery to acicular crystals and masses of a blackish color are widespread, especially as stains on other minerals. They mentioned "asbolane" as a Co-bearing variety of pyrolusite with a note that "Pyrolusite containing up to 20% cobalt has been observed."

Gebhard (1999) noted that black coatings on mottramite have been found to be coronadite, and that "The same occurrence is reported for other manganese oxides pyrolusite, chalcophanite and romanèchite."

chalcophanite; coronadite; mendipite (?); mottramite; romanèchite (?); willemite