Nambulite is a rare manganese silicate mineral typically found in metamorphic manganese ore deposits. It is most easily identified by its distinct reddish-brown color and triclinic crystal habit, often occurring alongside other manganese-rich minerals like rhodochrosite.
Is this nambulite?
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 nambulite with a known reference. Nambulite sits at Mohs 6.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: pale yellow.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: reddish orange brown.
- 5Look at form & habitCrystal system: triclinic. Typical habit: prismatic to tabular crystals, sometimes massive or granular.
Often confused with
Nambulite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Nambulite leaves pale yellow, Rhodonite leaves white.
How to tell apart: Streak differs, so Nambulite leaves pale yellow, Inesite leaves white.
How to tell apart: Nambulite is noticeably harder (Mohs 6.5 vs. 4.5-5); streak differs, so Nambulite leaves pale yellow, Pectolite leaves white; luster reads vitreous on Nambulite and silky, subvitreous on Pectolite.
Often found alongside nambulite
Minerals reported to co-occur with nambulite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- LiMn₄Si₅O₁₄(OH)
- Mohs hardness
- 6.5
- Density
- 3.53 g/cm³
- Colors
- Reddish orange brown
- Streak
- Pale yellow
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Triclinic
- Crystal habit
- Prismatic to tabular crystals, sometimes massive or granular
- Cleavage
- Perfect on {001}, distinct on {010} and {100}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In veinlets cutting braunite ores in chert (Funakozawa mine, Japan)
Where rockhounds find nambulite
Classic worldwide localities
- Funakozawa and Ohtaniyama mines, Ohno, Iwate Prefecture, and the Gozaisho mine, Iwaki, Fukushima Prefecture, Japan
Field-hunting tip
Where it forms: In veinlets cutting braunite ores in chert (Funakozawa mine, Japan). If you start seeing braunite, albite, neotocite in float, you are in the right ground. Typical habit: prismatic to tabular crystals, sometimes massive or granular. Train your eye for that shape before scanning the outcrop.
Common questions
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Find nambulite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
