Chalcostibite is a rare sulfide mineral with the chemical formula CuSbS₂, composed of copper, antimony, and sulfur. It belongs to the class of sulfide minerals and is characterized by its orthorhombic crystal structure.
Description
Chalcostibite typically occurs as steel‑gray to black, metallic‑lustered crystals or massive aggregates. The mineral exhibits a black streak and is opaque. Its Mohs hardness ranges from 2.5 to 3, and it has a relatively high specific gravity, generally reported between 4.9 and 5.0.
Crystallography
- Crystal system: Orthorhombic
- Space group: Pnma (or equivalent orthorhombic setting)
The orthorhombic symmetry results in prismatic crystals that may display well‑developed faces, although well‑formed crystals are uncommon in nature.
Physical Properties
| Property | Value |
|---|---|
| Color | Steel‑gray to black |
| Luster | Metallic |
| Streak | Black |
| Hardness | 2.5–3 (Mohs) |
| Specific gravity | 4.9–5.0 |
| Cleavage | Poor to indistinct |
| Fracture | Conchoidal to uneven |
Occurrence
Chalcostibite is primarily found in hydrothermal vein deposits that are rich in antimony and copper. It is commonly associated with minerals such as stibnite (Sb₂S₃), tetrahedrite ((Cu,Fe)₁₂Sb₄S₁₃), and chalcopyrite (CuFeS₂). Notable localities include:
- The Harz Mountains of Germany
- The Antimony district of Romania (e.g., the Baia Sprie area)
- Various sites in the United States, such as the Silver Valley of Idaho
These occurrences are typically of low to moderate grade, and chalcostibite is considered a minor source of copper and antimony.
History and Etymology
The name chalcostibite derives from the Greek word χαλκός (chalkos), meaning “copper,” combined with stibium, the Latin name for antimony. The mineral was first described in the mid‑19th century; early literature records its identification in European antimony mining districts, though precise discovery details vary among sources.
Uses
Because of its rarity and the modest concentrations of copper and antimony it contains, chalcostibite has no significant industrial application. It is of interest principally to mineral collectors and researchers studying sulfosalt mineralogy.
References
- Palache, C., H. Berman, and C. Frondel. Dana’s System of Mineralogy, 7th ed., Wiley, 1962.
- Mindat.org. “Chalcostibite.” Accessed 2026.
- Handbook of Mineralogy. “Chalcostibite.” Accessed 2026.