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, so Chalcostibite leaves lead-gray, Tetrahedrite leaves black.
How to tell apart: Streak differs, so 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, 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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