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. Streak: yellow.
- 3Read the lusterHold the specimen under a strong light. Luster: adamantine to vitreous and silky, earthy when massive.
- 4Match the color rangeCompare against the expected color range: greenish yellow, light yellow.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic.
Often confused with
Sklodowskite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Sklodowskite leaves yellow, Uranophane leaves yellowish white; luster reads adamantine to vitreous and silky, earthy when massive on Sklodowskite and vitreous on Uranophane.
How to tell apart: Kasolite is the harder of the two (Mohs 4-5 vs. ~2-3); streak differs, so Sklodowskite leaves yellow, Kasolite leaves pale yellow-brown; luster reads adamantine to vitreous and silky, earthy when massive on Sklodowskite and subadamantine to greasy, dull to earthy when massive on Kasolite.
How to tell apart: Streak differs, so Sklodowskite leaves yellow, Boltwoodite leaves white; luster reads adamantine to vitreous and silky, earthy when massive on Sklodowskite and pearly; radial aggregates vitreous to silky; dull to earthy in microcrystalline pseudomorphs 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
- 3.54 g/cm³
- Streak
- Yellow
- Luster
- Adamantine to vitreous and silky, earthy when massive
- Transparency
- Transparent to translucent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic
- Cleavage
- Perfect on {100}
- Fluorescence
- Bright green under SW UV
- Rarity
- Uncommon
- Uses
- Collector
- Host rock
- A rare secondary mineral formed by the action of silica-bearing waters on uraninite or earlier-formed secondary uranium minerals
Where rockhounds find sklodowskite
Classic worldwide localities
- Grants district, McKinley Co., New Mexico, USA
- Oyler Tunnel claim, near Fruita, Wayne Co., and from the Honeycomb Hills, Juab Co., Utah, USA
- New Haven mine, Crook Co., Wyoming, USA
- Ross-Adams mine, Bokan Mountain, Prince of Wales Island, Alaska, USA
- Shinkolobwe, Katanga Province, Congo (Shaba Province, Zaire)
- Santo Domingo mine, Santa Eulalia, Chihuahua, Mexico
Field-hunting tip
Where it forms: A rare secondary mineral formed by the action of silica-bearing waters on uraninite or earlier-formed secondary uranium minerals. If you start seeing kasolite, soddyite, torbernite in float, you are in the right ground. Typical habit: prismatic. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify sklodowskite?+
Where is sklodowskite found?+
Is sklodowskite safe to handle?+
What rocks look like sklodowskite?+
What minerals are found with sklodowskite?+
What kind of rock does sklodowskite form in?+
What is sklodowskite used for?+
Find sklodowskite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
