Feitknechtite is a rare manganese hydroxide mineral that most commonly occurs as a pseudomorph after pyrochroite. Collectors often find it as earthy or massive coatings in manganese-rich ore deposits, where it is frequently associated with hausmannite.
Is this feitknechtite?
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 feitknechtite with a known reference. Feitknechtite sits at Mohs 2.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Feitknechtite leaves a brown streak.
- 3Read the lusterHold the specimen under a strong light. Feitknechtite typically shows a dull luster.
- 4Match the color rangeCompare against the expected color range: brown, black, orange-brown.
- 5Look at form & habitCrystal system: trigonal. Typical habit: pseudomorphs, massive, earthy, crusts.
Often confused with
Feitknechtite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Manganite is the harder of the two (Mohs 4 vs. 2.5); streak differs — Feitknechtite leaves brown, Manganite leaves dark reddish-brown; luster reads dull on Feitknechtite and submetallic on Manganite.
How to tell apart: Hausmannite is the harder of the two (Mohs 5-5.5 vs. 2.5); streak differs — Feitknechtite leaves brown, Hausmannite leaves brownish-red; luster reads dull on Feitknechtite and submetallic on Hausmannite.
How to tell apart: Streak differs — Feitknechtite leaves brown, Pyrochroite leaves white; luster reads dull on Feitknechtite and pearly on Pyrochroite.
Often found alongside feitknechtite
Minerals reported to co-occur with feitknechtite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- β-MnO(OH)
- Mohs hardness
- 2.5
- Density
- 3.5 g/cm³
- Colors
- Streak
- Brown
- Luster
- Dull
- Transparency
- Opaque
- Crystal system
- Trigonal
- Crystal habit
- Pseudomorphs, Massive, Earthy, Crusts
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Manganese Deposits
- Typical price
- $20-150 thumbnail
Where rockhounds find feitknechtite
Classic worldwide localities
- Franklin, New Jersey (USA)
- Långban, Sweden
- Postmasburg, South Africa
Field-hunting tip
Look in hydrothermal manganese deposits country — that is the host setting where feitknechtite typically forms. If you start seeing hausmannite, pyrochroite, calcite in float, you are in the right ground. Field specimens usually show a pseudomorphs, massive, earthy, crusts habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find feitknechtite on the map
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