Chalcostibite is a rare copper antimony sulfide typically found in hydrothermal deposits. It is often identified by its metallic lead-gray color and striated tabular crystal habits, frequently occurring in association with stibnite.
Is this chalcostibite?
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 chalcostibite with a known reference. Chalcostibite sits at Mohs 3-4 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Chalcostibite leaves a lead-gray streak.
- 3Read the lusterHold the specimen under a strong light. Chalcostibite typically shows a metallic luster.
- 4Match the color rangeCompare against the expected color range: lead-gray, steel-gray, iron-black.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: tabular to prismatic crystals, often striated.
Often confused with
Chalcostibite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Chalcostibite leaves lead-gray, Tetrahedrite leaves black.
How to tell apart: Streak differs — Chalcostibite leaves lead-gray, Bournonite leaves steel-gray.
How to tell apart: Chalcostibite is noticeably harder (Mohs 3-4 vs. 2).
Often found alongside chalcostibite
Minerals reported to co-occur with chalcostibite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CuSbS₂
- Mohs hardness
- 3-4
- Density
- 5.0 g/cm³
- Streak
- Lead-gray
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Orthorhombic
- Crystal habit
- Tabular to Prismatic Crystals, Often Striated
- Cleavage
- Perfect in One Direction
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Veins
- Typical price
- $20-150 per specimen depending on size and crystal quality
Where rockhounds find chalcostibite
Classic worldwide localities
- Wolfsberg, Germany
- Huancavelica, Peru
- Pribram, Czech Republic
- Oruro, Bolivia
Field-hunting tip
Look in hydrothermal veins country — that is the host setting where chalcostibite typically forms. If you start seeing stibnite, chalcopyrite, galena in float, you are in the right ground. Field specimens usually show a tabular to prismatic crystals, often striated habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify chalcostibite?+
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Find chalcostibite on the map
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