Ribbeite is a rare manganese silicate member of the humite group, typically occurring in metamorphosed manganese deposits. It is most often found as granular masses or small prismatic crystals in association with other manganese minerals like hausmannite and jacobsite.
Is this ribbeite?
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 ribbeite with a known reference. Ribbeite sits at Mohs ~5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: light pink.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: pink.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: granular to prismatic crystals.
Often confused with
Ribbeite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Chondrodite is the harder of the two (Mohs 6-6.5 vs. ~5); streak differs, so Ribbeite leaves light pink, Chondrodite leaves gray.
How to tell apart: Humite is the harder of the two (Mohs 6 vs. ~5); streak differs, so Ribbeite leaves light pink, Humite leaves white.
How to tell apart: Clinohumite is the harder of the two (Mohs 6 vs. ~5); streak differs, so Ribbeite leaves light pink, Clinohumite leaves white.
Often found alongside ribbeite
Minerals reported to co-occur with ribbeite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Mn₅(SiO₄)₂(OH)₂
- Mohs hardness
- ~5
- Density
- 3.90 g/cm³
- Colors
- Streak
- Light pink
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Orthorhombic
- Crystal habit
- Granular to prismatic crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In mineralogically distinct layers, in tectonically transported and boudinaged manganese-rich lenses within dolostones, apparently formed under prograde metamorphic conditions
Where rockhounds find ribbeite
Classic worldwide localities
- Kombat mine, 49 km south of Tsumeb, Namibia
Field-hunting tip
Where it forms: In mineralogically distinct layers, in tectonically transported and boudinaged manganese-rich lenses within dolostones, apparently formed under prograde metamorphic conditions. If you start seeing alleghanyite, manganoan calcite, pyrochroite in float, you are in the right ground. Typical habit: granular to prismatic crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify ribbeite?+
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What rocks look like ribbeite?+
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Find ribbeite on the map
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