Psilomelane: The mineral psilomelane information and pictures

About

Psilomelane describes barium manganese hydroxides that do not form in visible crystals. Originally recognized as an individual mineral species, Psilomelane was discredited by the IMA in 1982. However, the name is still in use today, describing manganese hydroxides such as Romanechite and Hollandite that are not specifically identified and sometimes even admixed together.

Psilomelane can be banded with Pyrolusite, with alternating layers of light and dark gray bands. It is named after the Green term "psilos", meaning smooth, and "melas", meaning black.

Crystal Forms & Aggregates

Does not occur in individual crystals. Habits include botryoidal, mammilary, reniform, stalactitic, dendritic, arborescent, encrusting, massive, and earthy.

Striking Features

Color, streak, and association with other manganese minerals

Environment

As a secondary mineral in hydrothermal replacement deposits, in sandstones, limestones, and clays.

Uses

Psilomelane is an ore of manganese. The banded form combined with Pyrolusite is sometimes polished as a collectors species and as a minor gemstone.

Noteworthy Localities

Psilomelane occurs in many manganese deposits worldwide, often in uninteresting forms. Only few localities have produced any remarkable specimens. Fuzzy, hair-like masses associated with Pyrolusite form a very unique habit from the Tower mine, Luis Lopez Manganese District, Socorro Co., New Mexico. Specimens have also been found in Taouz, Er Rachidia Province, Morocco; Ironwood, Gogebic County, Michigan; Bisbee, Cochise Co., Arizona; and Austinville, Wythe Co., Virginia.

Common Mineral Associations

Barite, Pyrolusite, Quartz, Hematite

Distinguishing Similar Minerals

Pyrolusite - Most commonly in crystallized aggregates, which are lacking in Psilomelane.
Hematite - Has a red streak.
Goethite - Yellow streak, lower specific gravity, usually a darker color.

Psilomelane

Abouti

Crystal Forms & Aggregatesi

Striking Featuresi

Environmenti

Usesi

Noteworthy Localitiesi

Common Mineral Associationsi

Distinguishing Similar Mineralsi

Photos