Bismutohauchecornite
Chemical formula: Ni<sub>9</sub>Bi<sub>2</sub>S<sub>8</sub>
Bismutohauchecornite is a rare nickel bismuth sulfide, forming tabular crystals with a metallic luster.
Properties
- Mohs hardness
- 5.5
- Luster
- Metallic
- Streak
- Black
- Density
- 7.35
- Cleavage
- Perfect on {001}
- Fracture
- Uneven
- Transparency
- Opaque
- Crystal system
- Tetragonal
Diagnostic features
## Identification Amateur identification of bismutohauchecornite is practically impossible due to its occurrence as tiny inclusions in other sulfides. Identification requires advanced laboratory methods, such as chemical composition analysis (EDS/WDS) and reflected light microscopy (ore microscopy). Its creamy white color in reflected light and anisotropy are characteristic. ## Distinguishing from Similar Minerals It can be confused with other minerals from the hauchecornite group (hauchecornite, arsenohauchecornite, tellurohauchecornite), as well as with pentlandite, millerite, or other nickel and bismuth sulfides. Definitive differentiation is only possible based on detailed chemical analysis. ## Crystal Forms Crystals are typically tabular or lamellar, with a square or rectangular cross-section. They reach sizes up to 2 mm. They occur as individual crystals or granular aggregates embedded in other minerals.
Geological environment
## Genesis Bismutohauchecornite is a mineral of hydrothermal origin. It forms in ore veins rich in nickel, bismuth, arsenic, and antimony, cutting ultramafic rocks. It is one of the later minerals to crystallize in the hydrothermal sequence. ## Mineral Associations It most commonly co-occurs with millerite, pentlandite, chalcopyrite, gersdorffite, ullmannite, native bismuth, maucherite, and also with minerals from the hauchecornite group. ## Localities The most important and well-documented bismutohauchecornite localities worldwide include: - Vermilion Mine, Sudbury District, Ontario, Canada (type locality). - Oktyabrskoye deposit, Norilsk region, Russia. - Igdlokunguak Mine No. 2, Appat, Qaasuitsup Municipality, Greenland. - Riwaka Igneous Complex, Nelson, New Zealand.
Rarity
Very rare
For collectors
## Quality Criteria The quality of a bismutohauchecornite specimen is primarily determined by the size and degree of crystal development, although these rarely exceed 1-2 mm. The most prized specimens are those where crystals are clearly visible, undamaged, and embedded in a contrasting rock matrix or co-occur with well-defined crystals of other minerals, e.g., millerite. The purity of the crystal itself is not a key criterion, as the mineral is opaque. ## Popular Localities Specimens from the type locality, the Vermilion Mine in Canada, have particular historical value. Research material also comes from the Oktyabrskoye deposit in Russia. Due to its extreme rarity, any specimen with a documented locality is valuable to specialized collectors.
Care and storage
## Cleaning Bismutohauchecornite specimens, usually small inclusions in other minerals, practically do not require cleaning. If necessary, use only compressed air to remove dust. Avoid contact with water and chemical agents. ## What to Avoid Avoid contact with acids and other chemicals that can react with sulfides. The mineral is brittle, so protect it from impacts and scratches. Do not heat it or subject it to ultrasound. ## Storage Store in stable conditions, in a closed display box, to protect it from dust, moisture, and mechanical damage. Due to its rarity and small size, it is recommended to store it in its original container with a label.