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. Streak: black.
- 3Read the lusterHold the specimen under a strong light. Luster: metallic.
- 4Match the color rangeCompare against the expected color range: lead gray, blue gray, dark gray.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: euhedral crystals, massive.
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 black, Bournonite leaves steel-gray to iron-black; luster reads metallic on Chalcostibite and brilliant to dull on Bournonite.
How to tell apart: Chalcostibite is noticeably harder (Mohs 3-4 vs. 2); streak differs, so Chalcostibite leaves black, Stibnite leaves lead-gray.
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
- 4.95 g/cm³
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Orthorhombic
- Crystal habit
- Euhedral crystals, massive
- Cleavage
- Perfect on {010}; less so on {001} and {100}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Associated with other sulfosalts and sulfides in hydrothermal veins
Where rockhounds find chalcostibite
Classic worldwide localities
- Wolfsberg, in the Harz Mountains, Germany (type locality)
- Capileira, Sierra Nevada, Granada Province, Spain
- Saint-Pons, Alpes-de-Haute-Provence, France
- Saint Gestraudi, near Brixlegg, Tirol, Austria
- Baia Mare (Nagybánya) and Baia Sprie (Felsőbánya), Romania
- Tereksai, Kyrgyzstan
Field-hunting tip
Where it forms: Associated with other sulfosalts and sulfides in hydrothermal veins. If you start seeing jamesonite, chalcopyrite, pyrite in float, you are in the right ground. Typical habit: euhedral crystals, massive. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify chalcostibite?+
Where is chalcostibite found?+
Is chalcostibite safe to handle?+
What rocks look like chalcostibite?+
What minerals are found with chalcostibite?+
What kind of rock does chalcostibite form in?+
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Find chalcostibite on the map
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