Sengierite is a rare copper uranyl vanadate that typically forms as thin, vibrant yellow platy crystals or earthy coatings. Collectors prize it for its bright color, though it is primarily sought after by advanced mineral enthusiasts due to its radioactive nature and specialized occurrence.
Is this sengierite?
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 sengierite with a known reference. Sengierite sits at Mohs 2.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: pale green.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous to adamantine.
- 4Match the color rangeCompare against the expected color range: green, yellow green.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: blocky, prismatic.
Often confused with
Sengierite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Sengierite leaves pale green, Tyuyamunite leaves light yellow; luster reads vitreous to adamantine on Sengierite and adamantine, pearly on {001}, may be dull to waxy if massive on Tyuyamunite.
How to tell apart: Streak differs, so Sengierite leaves pale green, Carnotite leaves strontian-yellow; luster reads vitreous to adamantine on Sengierite and dull, earthy; silky when crystalline on Carnotite.
Often found alongside sengierite
Minerals reported to co-occur with sengierite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Cu₂(UO₂)₂(VO₄)₂·8-10H₂O
- Mohs hardness
- 2.5
- Density
- 4.05 g/cm³
- Colors
- Streak
- Pale green
- Luster
- Vitreous to adamantine
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Blocky, prismatic
- Cleavage
- On {001}, perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A rare secondary mineral, deposited from solutions derived from primary uraninite
Where rockhounds find sengierite
Classic worldwide localities
- Cole shaft, Bisbee, Cochise Co., Arizona, and the Section 33 mine, Grants district, McKinley Co., New Mexico, USA
- Luiswishi copper mine, Lubumbashi, Congo
- Shinkolobwe and in the Ruiwe, Musonoi, and Mutoshi mines, Katanga Province, Congo (Shaba Province, Zaire)
- Malargüe district, Mendoza Province, Argentina
- Rabéjac uranium deposit, seven km south-southeast of Lodève, Hérault, France
- Argana Bigoudine area, Amelal, Morocco
Field-hunting tip
Where it forms: A rare secondary mineral, deposited from solutions derived from primary uraninite. If you start seeing volborthite, vandenbrandeite, malachite in float, you are in the right ground. Typical habit: blocky, prismatic. Train your eye for that shape before scanning the outcrop.
Common questions
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Find sengierite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
