Umangite
Umangite is a relatively rare copper selenide mineral with the chemical formula Cu3Se2. It is an opaque, dark blue-gray to violet mineral, often exhibiting a metallic luster. Umangite is typically found in hydrothermal deposits, often associated with other copper and selenium minerals such as clausthalite, berzelianite, and chalcopyrite.
Properties:
- Chemical Formula: Cu3Se2
- Crystal System: Tetragonal
- Color: Dark blue-gray to violet
- Luster: Metallic
- Streak: Dark gray
- Hardness (Mohs): 3
- Density: 7.2 g/cm3 (approximate)
- Cleavage: None observed
- Fracture: Uneven
- Occurrence: Hydrothermal deposits
Occurrence and Formation:
Umangite primarily occurs as a secondary mineral formed by the alteration of other copper and selenium minerals. It is typically found in low-temperature hydrothermal veins and in sedimentary deposits. Notable occurrences include localities in Germany, Sweden, the United States (Colorado, Montana), and Argentina.
Uses:
Umangite is not a major ore mineral due to its relative scarcity. However, it can be a locally important source of selenium and copper, particularly when found in association with other economically viable minerals. It is also sought after by mineral collectors for its unique color and crystal formations.
Distinguishing Features:
Umangite can be distinguished from similar minerals by its characteristic color, metallic luster, and association with other selenium-bearing minerals. X-ray diffraction analysis can provide definitive identification.