Pierrotite is a very rare thallium-arsenic sulfosalt primarily known from the unique Allchar deposit in North Macedonia. It typically appears as lead-gray acicular crystals that can be difficult to distinguish from other sulfosalts without advanced analytical techniques.
Is this pierrotite?
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 pierrotite with a known reference. Pierrotite 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. Pierrotite leaves a black streak.
- 3Read the lusterHold the specimen under a strong light. Pierrotite typically shows a metallic luster.
- 4Match the color rangeCompare against the expected color range: lead-gray, black.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: acicular crystals, striations on crystal faces.
Often confused with
Pierrotite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Pierrotite leaves black, Stibnite leaves lead-gray.
How to tell apart: Streak differs — Pierrotite leaves black, Realgar leaves orange-red; luster reads metallic on Pierrotite and resinous on Realgar.
How to tell apart: Streak differs — Pierrotite leaves black, Lorandite leaves cherry-red.
Often found alongside pierrotite
Minerals reported to co-occur with pierrotite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Tl₂Sb₁₀As₄S₁₈
- Mohs hardness
- 2.5
- Density
- 4.8 g/cm³
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Orthorhombic
- Crystal habit
- Acicular Crystals, Striations On Crystal Faces
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Mineral Deposits
- Typical price
- $50-300 per specimen
Where rockhounds find pierrotite
Classic worldwide localities
- Allchar, North Macedonia
Field-hunting tip
Look in hydrothermal mineral deposits country — that is the host setting where pierrotite typically forms. If you start seeing lorandite, stibnite, realgar in float, you are in the right ground. Field specimens usually show a acicular crystals, striations on crystal faces habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify pierrotite?+
Where is pierrotite found?+
How much is pierrotite worth?+
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Find pierrotite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
