Kahlerite is a rare secondary uranium phosphate-arsenate mineral belonging to the autunite group. It typically appears as bright yellow to yellow-green platy crystals that resemble autunite but are distinguished by their chemical composition and association with arsenic-rich environments.
Is this kahlerite?
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 kahlerite with a known reference. Kahlerite sits at Mohs 2-2.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: light yellow.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: yellow green, lemon.
- 5Look at form & habitCrystal system: tetragonal. Typical habit: tabular crystals, micaceous aggregates.
Often confused with
Kahlerite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Kahlerite leaves light yellow, Autunite leaves pale yellow.
How to tell apart: Streak differs, so Kahlerite leaves light yellow, Torbernite leaves pale green.
How to tell apart: Streak differs, so Kahlerite leaves light yellow, Meta-autunite leaves yellow; luster reads vitreous on Kahlerite and pearly to dull on Meta-autunite.
Often found alongside kahlerite
Minerals reported to co-occur with kahlerite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Fe(UO₂)₂(AsO₄)₂·12H₂O
- Mohs hardness
- 2-2.5
- Density
- 3.22 g/cm³
- Colors
- Streak
- Light yellow
- Luster
- Vitreous
- Transparency
- Semitransparent
- Crystal system
- Tetragonal
- Crystal habit
- Tabular crystals, micaceous aggregates
- Cleavage
- Perfect on {001}
- Fluorescence
- Bright yellow-green under UV
- Rarity
- Rare
- Uses
- Collector, Reference specimen
- Host rock
- A very rare secondary mineral in the oxidized zone of a uraninite-bearing iron deposit (Hüttenberg, Austria)
Where rockhounds find kahlerite
Classic worldwide localities
- Hüttenberg, Carinthia, Austria
- Sophia and St. Joseph mine dumps, near Wittichen, and at Menzenschwand, Black Forest, Germany
- Mas-d’Alary uranium deposit, three km south-southeast of Lodève, Hérault, France
- Southwick Cliffs, near Dalbeattie, Kirkcudbrightshire, Scotland
Field-hunting tip
Where it forms: A very rare secondary mineral in the oxidized zone of a uraninite-bearing iron deposit (Hüttenberg, Austria). If you start seeing arsenosiderite, scorodite, symplesite in float, you are in the right ground. Typical habit: tabular crystals, micaceous aggregates. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify kahlerite?+
Where is kahlerite found?+
Is kahlerite safe to handle?+
What rocks look like kahlerite?+
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Find kahlerite on the map
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