Florensovite

Chemical formula: Cu¹⁺(Cr³⁺₁.₅Sb⁵⁺₀.₅)S²⁻₄

A black, metallic sulfide from the linnaeite group, distinguished by its unique combination of copper, chromium, and antimony.

## Characteristics Florensovite is a rare sulfide mineral belonging to the carrollite subgroup. It forms very small, most often isometric (cubic) crystals, not exceeding 0.3 mm in size. It occurs as inclusions in other minerals, mainly in calcite. Its characteristic features are its black color and metallic luster. ## Physical Properties The hardness of florensovite on the Mohs scale is 5. It is an opaque mineral. Due to the small size of its crystals and its occurrence as inclusions, precise measurement of its density is difficult and has not been accurately determined. ## Colors and Varieties This mineral is uniform in color and occurs exclusively in black. No color varieties or commercial forms are known. ## History and Name Florensovite was discovered and described in 1989. Its name honors Nikolai Alexandrovich Florensov (1909-1986), a Russian geologist who made significant contributions to the study of the geology of Siberia and the Baikal region. ## Uses Due to its extreme rarity and microscopic size, florensovite has no industrial applications. It is of purely scientific interest and is an object of interest for specialized collectors of rare minerals.

Properties

Mohs hardness
5
Luster
Metallic
Density
0
Transparency
Opaque
Crystal system
Isometric

Diagnostic features

## Identification Identification of florensovite is possible almost exclusively through advanced laboratory methods, such as chemical composition analysis (EDS) using an electron microscope. In collecting conditions, identification relies on trust in the label and the reputation of the source. Visually, they are simply tiny, black, metallic inclusions in calcite. ## Distinguishing from Similar Minerals Due to its appearance and co-occurrence, it can be confused with other small, black sulfides or oxides. Distinguishing it from similar minerals of the linnaeite group (e.g., carrollite, siegenite) or from chromite is impossible without specialized chemical analysis. ## Crystal Forms Florensovite forms very small, well-developed isometric (cubic) crystals, usually not exceeding 0.3 mm. They occur as single, dispersed inclusions in the host rock.

Geological environment

## Genesis Florensovite forms under specific metamorphic conditions. It has been found in calcitic marbles that underwent contact metamorphism due to the intrusion of basic and ultrabasic rocks. Its components (copper, chromium, antimony) originate from primary sedimentary rocks enriched in organic matter. ## Mineral Associations This mineral co-occurs with calcite (which is its host rock), as well as with other minerals such as diopside, quartz, pyrite, chalcopyrite, sphalerite, galena, tetrahedrite, and also rare minerals like karelianite or eskolaite. ## Localities The only confirmed and described locality of florensovite in the world is its type locality – the Pereval marble quarry near the town of Sludyanka on Lake Baikal, in the Irkutsk Oblast, Russia.

Rarity

Extremely rare

For collectors

## Quality Criteria The quality of a florensovite specimen primarily depends on the confirmation of its identity by a reliable laboratory. Since the crystals are microscopic, their size, sharpness of edges, and luster (observed under a microscope) are the main criteria. The abundance of crystals on a given rock fragment and the presence of interesting associated minerals also enhance its attractiveness. ## Popular Localities The only source of florensovite specimens is the Pereval quarry in Russia. All specimens available on the collector's market originate from this single locality.

Care and storage

## Cleaning Specimens containing florensovite, which are most often fragments of the host rock (calcitic marble), can only be cleaned very carefully. A soft brush may be used to remove dust. Due to the microscopic size of the crystals, all mechanical contact should be avoided. ## What to Avoid Avoid contact with acids and other chemicals that may react with sulfides or the surrounding calcite. The mineral is stable, but like most sulfides, it can be sensitive to prolonged exposure to moisture and air, which could theoretically lead to its oxidation. ## Storage Specimens should be stored in stable conditions, in closed collector boxes or display cases, to protect them from dust and mechanical damage. The best way to display them is in a specialized "micromount" box, which protects the specimen and allows for observation under a microscope.

External references

Sources

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