Uraninite is the primary ore of uranium, often appearing as heavy, black, massive or botryoidal crusts. It is intensely radioactive and requires careful handling, storage, and specialized equipment for detection.
Is this uraninite?
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 uraninite with a known reference. Uraninite sits at Mohs 5-6 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Uraninite leaves a brownish-black to greenish-black streak.
- 3Read the lusterHold the specimen under a strong light. Uraninite typically shows a submetallic to dull luster.
- 4Match the color rangeCompare against the expected color range: black, brownish-black, gray.
- 5Look at form & habitCrystal system: cubic. Typical habit: massive, botryoidal, reniform, or rarely cubic crystals.
Often confused with
Uraninite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Uraninite leaves brownish-black to greenish-black, Magnetite leaves black; luster reads submetallic to dull on Uraninite and metallic on Magnetite.
How to tell apart: Streak differs — Uraninite leaves brownish-black to greenish-black, Iron Ore leaves reddish-brown to black; luster reads submetallic to dull on Uraninite and metallic to submetallic on Iron Ore.
Often found alongside uraninite
Minerals reported to co-occur with uraninite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- UO₂
- Mohs hardness
- 5-6
- Density
- 8.0-10.6 g/cm³
- Colors
- Streak
- Brownish-black to Greenish-black
- Luster
- Submetallic to Dull
- Transparency
- Opaque
- Crystal system
- Cubic
- Crystal habit
- Massive, Botryoidal, Reniform, Or Rarely Cubic Crystals
- Cleavage
- None
- Rarity
- Uncommon
- Uses
- Ore of Uranium, Collector
- Host rock
- Granite Pegmatites and Hydrothermal Veins
- Typical price
- $20-200 for specimens depending on size and provenance
Where rockhounds find uraninite
13 mapped spotsClassic worldwide localities
- Democratic Republic of the Congo
- Czech Republic
- Canada
- USA
- France
Field-hunting tip
Look in granite pegmatites and hydrothermal veins country — that is the host setting where uraninite typically forms. If you start seeing galena, chalcopyrite, pyrite in float, you are in the right ground. Field specimens usually show a massive, botryoidal, reniform, or rarely cubic crystals habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Utah, California, Idaho — start trip planning there.
Common questions
How do you identify uraninite?+
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Find uraninite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
