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, so 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, so Feitknechtite leaves brown, Hausmannite leaves brownish-red; luster reads dull on Feitknechtite and submetallic on Hausmannite.
How to tell apart: Streak differs, so 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, 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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