Pumpellyite-(Mn²⁺) is a rare member of the pumpellyite group, typically occurring in manganese-rich metamorphic environments. Collectors should look for its characteristic brownish-red radiating fibrous or needle-like crystal aggregates found in association with other manganese minerals.
Is this pumpellyite-(mn2+)?
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 pumpellyite-(mn2+) with a known reference. Pumpellyite-(Mn2+) 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 grayish pink.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: brownish pink.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: fibrous aggregates, radiating needles, radial prismatic groups.
Often confused with
Pumpellyite-(Mn2+) vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Pumpellyite-(Mn2+) leaves light grayish pink, Pumpellyite-(Mg) leaves white.
How to tell apart: Epidote is the harder of the two (Mohs 6-7 vs. ~5); streak differs, so Pumpellyite-(Mn2+) leaves light grayish pink, Epidote leaves grayish white.
Often found alongside pumpellyite-(mn2+)
Minerals reported to co-occur with pumpellyite-(mn2+). Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ca₂Mn²⁺Al₂(SiO₄)(Si₂O₇)(OH)₂·H₂O
- Mohs hardness
- ~5
- Density
- 3.34 g/cm³
- Colors
- Brownish pink
- Streak
- Light grayish pink
- Luster
- Vitreous
- Transparency
- Semitransparent
- Crystal system
- Monoclinic
- Crystal habit
- Fibrous aggregates, radiating needles, radial prismatic groups
- Cleavage
- One perfect, presumably {001}, seen in thin section
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In braunite ore in a syngenetic bedded manganese deposit developed in low-grade metamorphic rocks
Where rockhounds find pumpellyite-(mn2+)
Classic worldwide localities
- Ochiai mine, 3.5 km west of Barazawa, Yamanashi Prefecture, Japan
Field-hunting tip
Where it forms: In braunite ore in a syngenetic bedded manganese deposit developed in low-grade metamorphic rocks. If you start seeing braunite, piemontite, clinozoisite in float, you are in the right ground. Typical habit: fibrous aggregates, radiating needles, radial prismatic groups. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify pumpellyite-(mn2+)?+
Where is pumpellyite-(mn2+) found?+
What rocks look like pumpellyite-(mn2+)?+
What minerals are found with pumpellyite-(mn2+)?+
What kind of rock does pumpellyite-(mn2+) form in?+
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Find pumpellyite-(mn2+) on the map
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