Jianshuiite is a rare manganese oxide mineral typically found in sedimentary manganese ore deposits. It is often identified as soft, earthy, or pulverulent masses that look similar to other black manganese oxides, making positive identification dependent on laboratory analysis like XRD.
Is this jianshuiite?
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 jianshuiite with a known reference. Jianshuiite sits at Mohs 1-2 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Jianshuiite leaves a brownish black streak.
- 3Read the lusterHold the specimen under a strong light. Jianshuiite typically shows a dull luster.
- 4Match the color rangeCompare against the expected color range: black, brownish black.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: massive, powdery, or as thin coatings.
Often confused with
Jianshuiite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Jianshuiite leaves brownish black, Birnessite leaves brownish-black.
How to tell apart: Streak differs — Jianshuiite leaves brownish black, Todorokite leaves black; luster reads dull on Jianshuiite and submetallic on Todorokite.
How to tell apart: Romanèchite is the harder of the two (Mohs 5-6 vs. 1-2); streak differs — Jianshuiite leaves brownish black, Romanèchite leaves shiny brownish black; luster reads dull on Jianshuiite and submetallic to dull on Romanèchite.
Often found alongside jianshuiite
Minerals reported to co-occur with jianshuiite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- MgMn³⁺₂O₅·3H₂O
- Mohs hardness
- 1-2
- Density
- 2.8-2.9 g/cm³
- Colors
- Streak
- Brownish Black
- Luster
- Dull
- Transparency
- Opaque
- Crystal system
- Monoclinic
- Crystal habit
- Massive, Powdery, Or as Thin Coatings
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Sedimentary Manganese Deposits
- Typical price
- $20-100 per specimen
Where rockhounds find jianshuiite
Classic worldwide localities
- Jianshui, Yunnan, China
- various manganese deposits worldwide
Field-hunting tip
Look in sedimentary manganese deposits country — that is the host setting where jianshuiite typically forms. If you start seeing birnessite, todorokite, goethite in float, you are in the right ground. Field specimens usually show a massive, powdery, or as thin coatings habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find jianshuiite on the map
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