Berthierite is a relatively uncommon iron antimony sulfide typically found in hydrothermal vein deposits. It is often confused with stibnite, but it lacks the characteristic highly flexible, sectile nature of stibnite and typically exhibits a more brittle, metallic character.
Is this berthierite?
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 berthierite with a known reference. Berthierite sits at Mohs 2-3, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: dark brownish gray.
- 3Read the lusterHold the specimen under a strong light. Luster: metallic.
- 4Match the color rangeCompare against the expected color range: dark steel gray, dark brownish gray.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: acicular, fibrous, massive.
Often confused with
Berthierite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Berthierite leaves dark brownish gray, Stibnite leaves lead-gray.
How to tell apart: Streak differs, so Berthierite leaves dark brownish gray, Jamesonite leaves black. grayish.
How to tell apart: Arsenopyrite is the harder of the two (Mohs 5.5-6 vs. 2-3); streak differs, so Berthierite leaves dark brownish gray, Arsenopyrite leaves black.
Often found alongside berthierite
Minerals reported to co-occur with berthierite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- FeSb₂S₄
- Mohs hardness
- 2-3
- Density
- 4.64 g/cm³
- Colors
- Dark steel grayDark brownish gray
- Streak
- Dark brownish gray
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Orthorhombic
- Crystal habit
- Acicular, fibrous, massive
- Cleavage
- Prismatic, indistinct
- Rarity
- Uncommon
- Uses
- Collector, Reference
- Host rock
- In low-temperature hydrothermal antimony veins, in portions deficient in sulfur
Where rockhounds find berthierite
Classic worldwide localities
- Chazelles, Auvergne (type locality), Pontgibaud, Puy-de-Dôme, and Valcros, Provence, France
- Herja (Kisbánya), Baia Mare (Nagybánya) district, and Baia Sprie (Felsőbánya), Romania
- Příbram and Kutná Hora, Czech Republic
- Bräunsdorf, near Freiberg, Saxony, Germany
- Ribnova, southern Rhodope Mountains, Bulgaria
- Niccioleta mine, Tuscany, Italy
Field-hunting tip
Where it forms: In low-temperature hydrothermal antimony veins, in portions deficient in sulfur. If you start seeing stibnite, arsenopyrite, pyrite in float, you are in the right ground. Typical habit: acicular, fibrous, massive. Train your eye for that shape before scanning the outcrop.
Common questions
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Find berthierite on the map
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