Watkinsonite is a rare lead-copper-bismuth selenide mineral typically found as microscopic grains embedded in other sulfide or selenide minerals. It is primarily identified through mineralogical analysis, such as electron microprobe or X-ray diffraction, as it rarely forms distinct macroscopic crystals.
Is this watkinsonite?
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 watkinsonite with a known reference. Watkinsonite sits at Mohs 3.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: black.
- 3Read the lusterHold the specimen under a strong light. Luster: metallic.
- 4Match the color rangeCompare against the expected color range: black.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: anhedral grains.
Often confused with
Watkinsonite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Watkinsonite is noticeably harder (Mohs 3.5 vs. 2.5-2.75); streak differs, so Watkinsonite leaves black, Galena leaves lead-gray.
How to tell apart: Streak differs, so Watkinsonite leaves black, Clausthalite leaves grayish black.
Often found alongside watkinsonite
Minerals reported to co-occur with watkinsonite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- PbCu₂Bi₄(Se,S)₈
- Mohs hardness
- 3.5
- Density
- 7.82 g/cm³
- Colors
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Monoclinic
- Crystal habit
- Anhedral grains
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In vein-type uranium deposits with other tellurides and selenides
Where rockhounds find watkinsonite
Classic worldwide localities
- Otish Mountains uranium deposit, Quebec, Canada
- El Dragón mine, Antonio Quijarro Province, Department of Potosí, Bolivia, From the Zálesí uranium deposit, Czech Republic, and the Niederschlema-Alberoda U-Se-polymetallic deposit, western Erzgebirge, Germany
Field-hunting tip
Where it forms: In vein-type uranium deposits with other tellurides and selenides. If you start seeing skippenite, soucekite, clausthalite in float, you are in the right ground. Typical habit: anhedral grains. Train your eye for that shape before scanning the outcrop.
Common questions
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Find watkinsonite on the map
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