Nekrasovite

Chemical formula: Cu¹⁺₉Cu²⁺₄V³⁺Sn⁴⁺₃S²⁻₁₆

Nekrasovite is a rare copper, vanadium, and tin sulfide, characterized by its metallic luster and pale brown color with a pinkish hue.

## Characteristics Nekrasovite is a complex sulfide belonging to the germanite group. It forms very small, irregular grains, usually not exceeding 0.2 mm in size, occurring in aggregates with other sulfides. Its characteristic visual features are a metallic luster and a specific, pale brown color with a noticeable pinkish hue. ## Physical Properties This mineral is opaque and exhibits a hardness of 4.5 on the Mohs scale. It has a metallic luster. Its density has not been precisely determined. ## Colors and Varieties Nekrasovite occurs in a uniform, pale brown color, which often has a pinkish hue. No color or commercial varieties are known. ## History and Name The mineral was first described in 1984. Its name commemorates Ivan Yakovlevich Nekrasov (1929-2000), a Russian mineralogist and expert in ore deposits, who worked at the Institute of Experimental Mineralogy of the Russian Academy of Sciences in Chernogolovka. ## Uses Due to its extreme rarity, nekrasovite has no industrial application and is solely an object of scientific interest and a collector's item for specialized micromineral collectors.

Properties

Mohs hardness: 4.5
Luster: Metallic
Density: 0
Transparency: Opaque
Crystal system: Isometric

Diagnostic features

## Identification Identification of nekrasovite is possible almost exclusively through advanced laboratory methods, such as chemical composition analysis (EDS/WDS) and X-ray diffraction (XRD). In collector settings, identification relies on a label from a confirmed locality. Visually, it can be suspected based on its pale brown color with a pinkish hue and metallic luster in association with other rare sulfides. ## Distinguishing from Similar Minerals It can be confused with other minerals from the germanite group, such as germanite, renierite, or briartite, which have a similar appearance and co-occur in the same environments. Definitive differentiation requires chemical analysis to determine vanadium and tin content. ## Crystal Forms Nekrasovite occurs as anhedral (irregular) grains and grain aggregates. Well-formed crystals have not been observed.

Geological environment

## Genesis Nekrasovite forms through hydrothermal processes in quartz-barite veins, associated with gold and sulfide deposits. It forms in paragenesis with other rare ore minerals. ## Mineral Associations This mineral co-occurs with luzonite, mawsonite, stannoidite, chalcopyrite, native gold, pyrite, tennantite, germanite, renierite, briartite, barite, and quartz. ## Localities The only confirmed and typical occurrence of nekrasovite worldwide is the Kairagach gold deposit in the Ohangaron district, Tashkent region, Uzbekistan.

Rarity

Extremely rare

For collectors

## Quality Criteria The quality of a nekrasovite specimen primarily depends on the richness and size of the aggregates within the host rock. Since the mineral is microscopic, samples where it is clearly visible and occurs alongside other rare minerals are most valued, as this increases the scientific and documentary value of the specimen. Precise identification confirmed by analysis is crucial. ## Popular Localities The only source of collector specimens is the type locality – the Kairagach deposit in Uzbekistan. All specimens available on the market originate from this single location.

Care and storage

## Cleaning Nekrasovite specimens, typically microscopic grains within the host rock, do not require cleaning. Any attempt at mechanical or chemical cleaning may irreversibly damage or destroy the mineral. ## What to Avoid Avoid contact with chemicals, acids, and cleaning agents. As a sulfide, it may be sensitive to moisture and oxidation in the long term. Protect it from extreme temperatures and direct sunlight. ## Storage Specimens containing nekrasovite are best stored under stable conditions, in sealed, dry "micromount" containers, to protect them from dust, moisture, and mechanical damage.