Vasilite
Chemical formula: (Pd,Cu)₁₆(S,Te)₇
Vasilite is an extremely rare palladium and copper sulfide and telluride, forming microscopic, metallic grains in ultramafic rocks.
Properties
- Mohs hardness
- 4.5-5
- Color
- Steel-gray
- Luster
- Metallic
- Streak
- Black
- Density
- 0
- Fracture
- Irregular/Uneven
- Transparency
- Opaque
- Crystal system
- Isometric
Diagnostic features
## Identification Identification of vasilite is impossible without advanced laboratory techniques. It requires analysis in reflected light on a polished petrographic section and confirmation of chemical composition using an electron microprobe (EDS/WDS). In reflected light, it is characterized by a creamy-white color with a pinkish tint and a lack of anisotropy. ## Distinguishing from Similar Minerals It can be confused with other microscopic sulfides and tellurides of platinum-group metals, such as kotulskite, majakite, or atokite. Definitive differentiation is possible only through chemical analysis, which reveals the characteristic proportion of palladium, copper, sulfur, and tellurium for vasilite. ## Crystal Forms Vasilite crystals have not been observed. This mineral forms only very fine, irregular, anhedral grains and aggregates of grains within other minerals.
Geological environment
## Genesis Vasilite forms as a result of hydrothermal or magmatic processes within differentiated intrusions of ultramafic and mafic rocks, rich in copper, nickel, and platinum-group elements. It forms in the late stages of crystallization, filling spaces between previously formed minerals. ## Mineral Associations This mineral co-occurs with other sulfides and tellurides. It is most commonly associated with: chalcopyrite, bornite, kotulskite, majakite, sobolevskite, sperrylite, and also native gold. ## Localities The type locality, from which vasilite was first described, is the Oktyabrskoye copper-nickel deposit in the Norilsk region of Siberia, Russia. This is its main and most well-known occurrence. It has also been reported in the Bushveld Complex in South Africa.
Rarity
Extremely rare
For collectors
## Quality Criteria The quality of a vasilite specimen is primarily assessed based on the confirmation of its presence through analysis. Since the grains are microscopic, the collector's value lies in the mere fact of possessing a documented rock fragment (most often a polished section) from the type locality. The size of the grains, though always microscopic, and the richness of the association with other rare platinum-group minerals can increase the scientific and collector's value of the specimen.
Care and storage
## Cleaning Specimens containing vasilite are typically polished petrographic sections or rock fragments. Cleaning is neither recommended nor necessary. If needed, compressed air can be used to remove dust. ## What to Avoid Avoid contact with chemicals, acids, and ultrasonic cleaners, which could damage both the delicate vasilite grains and the surrounding rock matrix. Polished sections should be protected from scratching. ## Storage Specimens with vasilite should be stored under stable conditions, away from dust and moisture, preferably in "micromount" boxes or special containers for polished sections, to prevent mechanical damage.