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 — 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 — 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 — that is 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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