Klajite is a rare secondary uranium phosphate mineral that typically forms as thin, platy crystals in oxidized hydrothermal veins. Collectors prize its vibrant yellow-green color and intense fluorescence under UV light, though it must be handled with care due to its radioactive nature.
Is this klajite?
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 klajite with a known reference. Klajite sits at Mohs 2-3, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Klajite leaves a yellow streak.
- 3Read the lusterHold the specimen under a strong light. Klajite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: yellow, yellow-green.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: platy crystals, crusts, tabular aggregates.
Often confused with
Klajite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Klajite leaves yellow, Autunite leaves pale yellow; luster reads vitreous on Klajite and pearly on Autunite.
How to tell apart: Luster reads vitreous on Klajite and pearly on Meta-autunite.
How to tell apart: Streak differs, so Klajite leaves yellow, Torbernite leaves pale green.
Often found alongside klajite
Minerals reported to co-occur with klajite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- MgCu₄(UO₂)₂(PO₄)₄·20H₂O
- Mohs hardness
- 2-3
- Density
- 3.5-3.6 g/cm³
- Colors
- Streak
- Yellow
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Platy Crystals, Crusts, Tabular Aggregates
- Cleavage
- Perfect
- Fluorescence
- Bright Yellow-green Under UV
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Uranium Veins
- Typical price
- $50-300 per specimen depending on size and quality
Where rockhounds find klajite
Classic worldwide localities
- Jachymov, Czech Republic
- Krunkelbach Valley, Germany
Field-hunting tip
Look in hydrothermal uranium veins country, the host setting where klajite typically forms. If you start seeing uraninite, torbernite, autunite in float, you are in the right ground. Field specimens usually show a platy crystals, crusts, tabular aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find klajite on the map
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