Brusnitsynite

Chemical formula: Mn²⁺₃Cu¹⁺Pb²⁺As³⁺₃Sb³⁺₂S²⁻₁₂

Brusnitsynite is a very rare, black sulfosalt of lead, copper, manganese, arsenic, and antimony, occurring as tiny, acicular crystals.

## Characteristics Brusnitsynite is a complex sulfosalt belonging to the lillianite homologous series. It forms very tiny, acicular or hair-like crystals up to 1 mm long and only a few micrometers thick. These crystals often occur as tangled aggregates or radial clusters embedded in calcite. Visually, it is black and opaque, with a metallic luster. ## Physical Properties This mineral is characterized by a Mohs hardness of approximately 4. Its density, calculated based on the chemical formula and unit cell parameters, is 4.545 g/cm³. It is brittle, and its fracture is uneven. ## Colors and Varieties Brusnitsynite occurs exclusively in black. No colored or commercial varieties are known. ## History and Name The mineral's name honors Tamara Vasilyevna Brusnitsyna (1959–2002), a Russian mineralogist and crystallographer from St. Petersburg State University, for her contributions to the study of ore minerals. Brusnitsynite was approved as a new mineral species by the International Mineralogical Association (IMA) in 2003. It was discovered at the Vorontsovskoye gold deposit in the Sverdlovsk Oblast, Russia. ## Applications Due to its extreme rarity and microscopic crystal sizes, brusnitsynite has no industrial applications. It is of purely scientific significance and is of interest to specialized collectors of rare minerals.

Properties

Mohs hardness
4-0
Luster
Metallic
Density
4.545
Fracture
Irregular/Uneven
Transparency
Opaque
Crystal system
Monoclinic

Diagnostic features

## Identification Identification of brusnitsynite is impossible without advanced analytical methods, such as X-ray microanalysis (EDS/WDS) and X-ray diffraction (XRD). Visually, at the occurrence site, it can be suspected based on the presence of black, acicular or hair-like crystals in association with realgar, orpiment, and other sulfosalts. ## Differentiation from Similar Minerals It can be confused with many other acicular sulfosalts, such as jamesonite, boulangerite, or zinkenite. Definitive differentiation from these minerals requires specialized chemical analysis to determine its unique composition (presence of copper, manganese, lead, arsenic, and antimony in specific proportions). ## Crystal Forms Brusnitsynite forms elongated, acicular or hair-like crystals, which can reach up to 1 mm in length. They typically occur as tangled, felt-like masses or radial aggregates.

Geological environment

## Genesis Brusnitsynite forms under low-temperature hydrothermal conditions. At its type locality (Vorontsovskoye deposit), it was found in calcite veins cutting mineralized limestones. It is a mineral of the late stage of mineralization. ## Mineral Associations This mineral co-occurs with other hydrothermal minerals, such as realgar, orpiment, aktashite, getchellite, native sulfur, pyrite, and also with calcite, in which it forms inclusions. ## Localities The only confirmed locality for brusnitsynite in the world is its type locality: the Vorontsovskoye gold deposit, located in the Serov district of Sverdlovsk Oblast in the Urals, Russia.

Rarity

Extremely rare

For collectors

## Quality Criteria The quality of a brusnitsynite specimen primarily depends on the abundance and visibility of its microscopic crystals within the host rock (matrix), most often calcite. Specimens with clearly formed, dense clusters of acicular crystals are most desirable. Contrast with bright calcite enhances aesthetic value. Due to their microscopic nature, specimens are evaluated under magnification. ## Popular Localities The only source of brusnitsynite specimens is its type locality in Russia. All specimens available on the collector's market originate from this single location, making them extremely rare and sought after by collectors specializing in rare mineral species.

Care and storage

## Cleaning Brusnitsynite specimens are extremely delicate and usually occur as microscopic inclusions in other minerals, such as calcite. Mechanical cleaning is not recommended. If dust removal is necessary, compressed air can be used from a safe distance. ## What to Avoid Avoid contact with all chemicals, especially acids, which can react with sulfosalts and calcite. Protect the specimen from ultrasound, high temperatures, and sudden temperature changes. Due to its brittleness, avoid shocks and impacts. ## Storage Brusnitsynite specimens are best stored in stable conditions, in a sealed "micromount" box, to protect them from dust and mechanical damage. It is not sensitive to light, but protection from external factors is crucial for preserving the delicate crystals.

External references

Sources

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