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The Mineral manganite

Lustrous Manganite Crystal Grouping

Manganite is a mineral named for its dominating manganese content. It forms in manganese deposits, where it is more common than perceived as an uninteresting mineral. However, several localities produce very aesthetic, well-crystallized forms of Manganite that are highly lustrous. These exceptional examples, especially those from Ilfied in Germany, are rarities that are highly prized by collectors, with high-end collectors vying for the top specimens of this mineral. 

Chemical Formula

MnO(OH)

Color

Dark gray to black

Crystal System

Monoclinic

Properties

Streak
Reddish brown to black
Hardness
3.5 - 4
Transparency
Opaque
Specific Gravity
4.3 - 4.4
Luster
Submetallic
Cleavage
1,1
Fracture
Uneven
Tenacity
Brittle

Crystal Habits

Manganite is best known in aggregates of blocky and short prismatic crystals. Crystal aggregates are usually in disorganized clusters with the crystals coming out of all directions. Thick crystals are heavily striated lengthwise, and often exhibit curvature. Twinning, in both penetration twinning and contact twinning, is known. Additional habits include acicular, radiating, fibrous, plumose, mammilary, globular, grainy, and massive.

3D Crystal Atlas

Additional Information

Composition
Basic manganese hydroxide
In Group
Oxides; Hydroxides
Striking Features
Crystal habit, mode of occurrence, and streak
Environment
In low temperature hydrothermal replacement deposits, acid-rich bogs, and in manganese-rich hot springs.
Rock Type
Sedimentary, Metamorphic

Uses

Manganite has been used as an ore of manganese in the past. The classic, well-crystallized forms of Manganite from Germany make an important collector's mineral that is highly prized by collectors.

Noteworthy Localities

The premier locality for Manganite is Ilfeld, in the Harz Mountains, Thuringia, Germany, where it was found in exceptionally lustrous blocky crystals. The best of this seems to have come from the late 1800's, with no new recent discoveries of interest.

Large and often curved crystals are found in the Kalahari manganese field, in Northern Cape Province, South Africa - at the Wessels Mine in Hotazel; and at the N'Chwaning Mines in Kuruman. Radiating and fibrous Manganite, resembling Pyrolusite, has come from the Bölet Manganese Mines, Undenäs, Karlsborg, Sweden.

Lustrous blocky Manganite crystals in vugs, as well as sharp acicular crystals, have been mined in Canada at the Caland Mine, Atikokan, in the Rainy River District, Ontario. Also in Canada is Walton and Cheverie, Hants Co., Nova Scotia, which has produced fibrous crystal groupings. The historic Michigan iron-mining districts of Negaunee, in the Marquette iron range, Marquette Co.; and Ironwood, in the Gogebic iron range, Gogebic Co. have also produced Manganite specimens of interest.

Common Mineral Associations

Barite, Quartz, Pyrolusite, Calcite, Limonite, Siderite, Goethite

Distingushing Similar Minerals

Pyrolusite - Rarely forms in large crystals like Manganite; otherwise can be distinguished by streak.
Enargite - Luster is more metallic, and has a different streak.
Goethite - Greater hardness, more brown in color color, and has a different streak.
Hematite - Different crystal habits, greater hardness, more metallic luster.


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