Manganite is a manganese oxide mineral typically found as dark, striated, prismatic crystals. It is easily distinguished from other black manganese minerals by its characteristic dark reddish-brown streak. It is most commonly found in hydrothermal deposits associated with other manganese minerals and carbonates.
Is this manganite?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch manganite with a known reference. Manganite sits at Mohs 4, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: reddish brown to nearly black.
- 3Read the lusterHold the specimen under a strong light. Luster: submetallic.
- 4Match the color rangeCompare against the expected color range: dark gray, black, steel-gray, gray, grayish black.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: massive, prismatic, pseudo orthorhombic.
Often confused with
Manganite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Manganite leaves reddish brown to nearly black, Pyrolusite leaves black, bluish black; luster reads submetallic on Manganite and metallic on Pyrolusite.
How to tell apart: Psilomelane is the harder of the two (Mohs 5-6 vs. 4); streak differs, so Manganite leaves reddish brown to nearly black, Psilomelane leaves brownish black.
How to tell apart: Hausmannite is the harder of the two (Mohs 5.5 vs. 4); streak differs, so Manganite leaves reddish brown to nearly black, Hausmannite leaves dark reddish brown.
Often found alongside manganite
Minerals reported to co-occur with manganite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- MnO(OH)
- Mohs hardness
- 4
- Density
- 4.29-4.34 g/cm³
- Streak
- Reddish brown to nearly black
- Luster
- Submetallic
- Transparency
- Opaque, transparent on thin edges
- Crystal system
- Monoclinic
- Crystal habit
- Massive, prismatic, pseudo orthorhombic
- Cleavage
- {010}, perfect; {110} and {001}, good
- Rarity
- Common
- Uses
- Collector, Ore of manganese
- Host rock
- Formed in low-temperature hydrothermal or hot-spring manganese deposits; replacing other manganese minerals in sedimentary deposits; a component in some clay deposits and laterites
Where rockhounds find manganite
2 mapped spotsClassic worldwide localities
- Negaunee and Marquette districts, Marquette Co., Michigan, USA
- Powell’s Fort mine, near Woodstock, Shenandoah Co., Virginia, USA
- Lake Valley, Sierra Co., New Mexico, USA
- Ilfeld, Harz Mountains, and Ilmenau, Thuringia, Germany
- Botallack mine, St. Just, Cornwall, England
- Egremont, Cumbria, England
Field-hunting tip
Where it forms: Formed in low-temperature hydrothermal or hot-spring manganese deposits; replacing other manganese minerals in sedimentary deposits; a component in some clay deposits and laterites. If you start seeing pyrolusite, braunite, hausmannite in float, you are in the right ground. Typical habit: massive, prismatic, pseudo orthorhombic. Train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Utah. Start trip planning there.
Common questions
How do you identify manganite?+
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Can I find manganite in the United States?+
What rocks look like manganite?+
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Find manganite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
