Sklodowskite is a secondary uranium mineral characterized by its vibrant yellow, needle-like crystals that often form stunning radiating sunbursts. It is a highly sought-after specimen for advanced mineral collectors due to its intense green fluorescence and aesthetic habit, but requires careful handling due to its radioactivity.
Is this sklodowskite?
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 sklodowskite with a known reference. Sklodowskite 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. Sklodowskite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Sklodowskite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: yellow, pale yellow, greenish-yellow.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: acicular or fibrous crystals forming radiating sprays and crusts.
Often confused with
Sklodowskite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Sklodowskite leaves white, Uranophane leaves pale yellow.
How to tell apart: Kasolite is the harder of the two (Mohs 4-5 vs. 2-3); streak differs — Sklodowskite leaves white, Kasolite leaves yellow; luster reads vitreous on Sklodowskite and greasy on Kasolite.
How to tell apart: Streak differs — Sklodowskite leaves white, Boltwoodite leaves yellow; luster reads vitreous on Sklodowskite and pearly on Boltwoodite.
Often found alongside sklodowskite
Minerals reported to co-occur with sklodowskite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Mg(UO₂)₂(SiO₃OH)₂·6H₂O
- Mohs hardness
- 2-3
- Density
- 3.7-3.8 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Acicular or Fibrous Crystals Forming Radiating Sprays and Crusts
- Cleavage
- Perfect in One Direction
- Fluorescence
- Bright Green Under SW UV
- Rarity
- Uncommon
- Uses
- Collector
- Host rock
- Oxidized Zones of Uranium-bearing Hydrothermal Deposits
- Typical price
- $50-500 depending on specimen size and radioactivity intensity
Where rockhounds find sklodowskite
Classic worldwide localities
- Shinkolobwe Mine, Democratic Republic of the Congo
- Musonoi Mine, Democratic Republic of the Congo
- Jachymov, Czech Republic
- Margnac, France
- Pick's Claims, Utah, USA
Field-hunting tip
Look in oxidized zones of uranium-bearing hydrothermal deposits country — that is the host setting where sklodowskite typically forms. If you start seeing uraninite, becquerelite, curite in float, you are in the right ground. Field specimens usually show a acicular or fibrous crystals forming radiating sprays and crusts habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify sklodowskite?+
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Find sklodowskite on the map
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