Kummerite is a rare manganese iron aluminum phosphate, typically amber-yellow. It is a secondary mineral in pegmatite formed by the reaction of laueite with Al-bearing hydrothermal fluids. It was first described from the 57 ± 2 m level, Oberpfalz, Bavaria, Germany.
Is this kummerite?
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 kummerite with a known reference. Kummerite sits at Mohs 9, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: amber-yellow.
- 5Look at form & habitCrystal system: triclinic. Typical habit: prismatic crystals.
Often confused with
Kummerite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside kummerite
Minerals reported to co-occur with kummerite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Mn²⁺Fe³⁺Al(PO₄)₂(OH)₂·8H₂O
- Mohs hardness
- 9
- Density
- 2.34 g/cm³
- Colors
- Amber-yellow
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Triclinic
- Crystal habit
- Prismatic crystals
- Cleavage
- Good on {010}
- Rarity
- Rare
- Uses
- Gemstone, Collector
- Host rock
- A secondary mineral in pegmatite formed by the reaction of laueite with Al-bearing hydrothermal fluids
Where rockhounds find kummerite
Classic worldwide localities
- 57 ±Oberpfalz, Bavaria, Germany
Field-hunting tip
Where it forms: A secondary mineral in pegmatite formed by the reaction of laueite with Al-bearing hydrothermal fluids. If you start seeing zwieselite, al-bearing frondelite, jahnsite- in float, you are in the right ground. Typical habit: prismatic crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify kummerite?+
Where is kummerite found?+
What rocks look like kummerite?+
What minerals are found with kummerite?+
What kind of rock does kummerite form in?+
What is kummerite used for?+
Find kummerite on the map
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