Hübnerite
Chemical formula: Mn<sup>2+</sup>W<sup>6+</sup>O<sub>4</sub>
Hübnerite is a manganese tungstate, valued by collectors for its well-formed, often reddish crystals and high luster.
Properties
- Mohs hardness
- 4-4.5
- Luster
- Submetallic, Resinous
- Streak
- Reddish brown, Yellowish brown
- Density
- 7.12-7.3
- Cleavage
- Perfect on {010}
- Fracture
- Uneven
- Transparency
- Translucent to Opaque
- Crystal system
- Monoclinic
Diagnostic features
## Identification Hübnerite can be identified by its characteristic reddish-brown to black color, high density, metallic or resinous luster, and specific crystal forms – often flattened, tabular with striated faces. The reddish hue on thin edges and a reddish-brown streak are key diagnostic features.
Geological environment
## Genesis Hübnerite is a mineral of high-temperature hydrothermal veins, often associated with granitic intrusions. It also occurs in greisens, skarns, and as an accessory mineral in some granites and pegmatites. Due to its resistance to weathering, it can be found in alluvial deposits (river sands and gravels).
Rarity
Not very common
For collectors
## Quality Criteria The most prized hübnerite specimens are those with sharply terminated, well-formed crystals of intense, reddish-brown color and strong luster. Transparent or translucent crystals that show a deep red color when backlit are particularly sought after. The aesthetic appeal of a specimen is enhanced by its placement on a contrasting matrix, such as white quartz, and the presence of aesthetic twinning.
Care and storage
## Cleaning Hübnerite specimens should be cleaned very carefully, using a soft brush to remove dust. For heavier dirt, distilled water can be used. Due to its excellent cleavage, ultrasonic cleaners should be avoided, as they can cause crystals to fracture.