Semseyite is a lead antimony sulfosalt known for its distinctive tabular crystals with characteristically curved or serrated edges. It is most frequently encountered in hydrothermal sulfide deposits and is highly prized by collectors for its complex crystal morphology.
Is this semseyite?
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 semseyite with a known reference. Semseyite 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. Semseyite leaves a black streak.
- 3Read the lusterHold the specimen under a strong light. Semseyite typically shows a metallic luster.
- 4Match the color rangeCompare against the expected color range: lead-gray.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: tabular crystals, often with curved or serrated edges and striated faces.
Often confused with
Semseyite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside semseyite
Minerals reported to co-occur with semseyite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Pb₉Sb₈S₂₁
- Mohs hardness
- 2.5
- Density
- 5.9-6.1 g/cm³
- Colors
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Monoclinic
- Crystal habit
- Tabular Crystals, Often with Curved or Serrated Edges and Striated Faces
- Cleavage
- Good On {010}
- Rarity
- Uncommon
- Uses
- Collector
- Host rock
- Hydrothermal Veins
- Typical price
- $20-200 depending on specimen size and crystal perfection
Where rockhounds find semseyite
Classic worldwide localities
- Baia Sprie, Romania
- Herja Mine, Romania
- Wolfsberg, Germany
- Oruro, Bolivia
Field-hunting tip
Look in hydrothermal veins country — that is the host setting where semseyite typically forms. If you start seeing galena, sphalerite, stibnite in float, you are in the right ground. Field specimens usually show a tabular crystals, often with curved or serrated edges and striated faces habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find semseyite on the map
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