Nsutite is a manganese oxide mineral typically found as massive, botryoidal, or stalactitic crusts in manganese deposits. It is best identified by its distinctively hard, submetallic dark gray appearance and its frequent association with other manganese minerals like pyrolusite. Collectors primarily seek out specimens from its type locality in Nsuta, Ghana.
Is this nsutite?
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 nsutite with a known reference. Nsutite sits at Mohs 6.5-8.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: black.
- 3Read the lusterHold the specimen under a strong light. Luster: metallic to earthy.
- 4Match the color rangeCompare against the expected color range: dark gray, grayish black, black.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: earthy, massive.
Often confused with
Nsutite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Nsutite is noticeably harder (Mohs 6.5-8.5 vs. 4); streak differs, so Nsutite leaves black, Manganite leaves reddish brown to nearly black; luster reads metallic to earthy on Nsutite and submetallic on Manganite.
How to tell apart: Streak differs, so Nsutite leaves black, Psilomelane leaves brownish black; luster reads metallic to earthy on Nsutite and submetallic on Psilomelane.
Often found alongside nsutite
Minerals reported to co-occur with nsutite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Mn⁴⁺,Mn²⁺)(O,OH)₂
- Mohs hardness
- 6.5-8.5
- Density
- 4.24-4.67 g/cm³
- Streak
- Black
- Luster
- Metallic to earthy
- Transparency
- Opaque
- Crystal system
- Hexagonal
- Crystal habit
- Earthy, massive
- Cleavage
- None
- Rarity
- Uncommon
- Uses
- Collector, Ore of manganese
- Host rock
- Thought to be supergene, formed under alkaline oxidizing conditions deficient in barium and potassium
Where rockhounds find nsutite
Classic worldwide localities
- Philipsburg, Granite Co., Montana, and the Hardshell mine, Santa Cruz Co., Arizona, USA
- Nsuta, Ghana
- Mokuta, Ivory Coast
- Orient mine, Krugersdorp, Transvaal, and near Kuruman, Cape Province, South Africa
- Tartana, 32 km north of Drama, Macedonia
- Molango Piedras Negras, Hidalgo, Mexico
Field-hunting tip
Where it forms: Thought to be supergene, formed under alkaline oxidizing conditions deficient in barium and potassium. If you start seeing pyrolusite, cryptomelane, romanèchite in float, you are in the right ground. Typical habit: earthy, massive. Train your eye for that shape before scanning the outcrop.
Common questions
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Find nsutite on the map
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