Lebedevite

Chemical formula: K₄Na₁₄Cu²⁺₁₄O₈(As⁵⁺O₄)₈Cl₆

Lebedevite is an extremely rare copper, potassium, and sodium arsenate, forming unique, blue, spherical aggregates in volcanic FUMAROLE products.

## Characteristics Lebedevite is a mineral from the arsenate group, distinguished by its exceptionally complex chemical composition, including potassium, sodium, and copper. It forms characteristic, spherical or hemispherical aggregates with a radial internal structure, reaching up to 0.3 mm in diameter. Individual crystals within the aggregates are platy or lath-like. Due to its rarity and specific formation conditions, it is primarily of scientific interest. ## Physical Properties Lebedevite crystals are flexible and exhibit perfect, platy cleavage. The mineral has a vitreous luster and is transparent. Its hardness and density have not been precisely determined due to the small size and rarity of samples. ## Colors and Varieties Lebedevite occurs in a uniform, intense blue color. No color varieties or commercial forms are known. ## History and Name The mineral was named in honor of Vladimir Ivanovich Lebedev (1910–1989), a Russian geochemist and mineralogist from St. Petersburg University, in recognition of his contribution to geochemistry. It was approved by the International Mineralogical Association (IMA) in 2018. The type locality from which it originates is the Yadovitaya fumarole on Tolbachik volcano in Kamchatka, Russia. ## Uses Lebedevite has no industrial applications. Its significance is purely scientific and as a collector's item, as a unique and newly discovered mineral.

Properties

Luster
Vitreous
Streak
Blue
Cleavage
Perfect on {001}
Transparency
Transparent
Crystal system
Tetragonal

Diagnostic features

## Identification Lebedevite is identifiable by its unique occurrence in the form of blue, spherical aggregates with a radial structure. Its characteristic occurrence as a sublimation product in active volcanic fumaroles is also distinctive. ## Distinguishing from Similar Minerals It can be confused with other blue copper arsenates found in the same environment, such as eriochalcite or leningradite. Final differentiation requires advanced analytical methods, such as X-ray diffraction (XRD) or chemical analysis (EDS), due to visual similarity and co-occurrence. ## Crystal Forms The mineral forms spherulites (spherical aggregates) up to 0.3 mm in diameter, composed of radially arranged, platy or lath-like crystals.

Geological environment

## Genesis Lebedevite forms as a sublimation product in high-temperature, active volcanic fumaroles. It crystallizes directly from volcanic gases rich in arsenic, copper, chlorine, and alkali metals at temperatures of approximately 450-500°C. ## Mineral Associations This mineral co-occurs with other rare arsenates and sulfates formed under similar conditions. The most common associated minerals include: hematite, tenorite, aphthitalite, johillerite, eriochalcite, leningradite, arsmirandite, and arsenatrotitanite. ## Localities The only confirmed locality for lebedevite in the world is its type locality – the Yadovitaya fumarole on the second eruptive cone of the northern breach of the Great Fissure Eruption of Tolbachik volcano in Kamchatka, Russia.

Rarity

Extremely rare

For collectors

## Quality Criteria As a "micromount" type mineral, the quality of a specimen is primarily determined by the abundance and development of spherical aggregates on the rock matrix. The most prized samples are those with numerous, well-formed, intensely blue spherulites, clearly contrasting with the substrate. Association with other rare minerals from this locality is also important. ## Popular Localities The only source of lebedevite specimens is its type locality on Tolbachik volcano in Kamchatka. All samples available on the collector's market originate from this single location.

Care and storage

## Cleaning Due to its extreme rarity, small size, and fragility, lebedevite specimens should not be cleaned mechanically or chemically. Any contaminants should be left undisturbed. ## What to Avoid Avoid contact with water, chemicals, ultrasound, and sudden temperature changes. The mineral is likely sensitive to moisture and acids. It should be protected from dust and vibrations. ## Storage Specimens should be stored exclusively in specialized, sealed "micromount" containers, away from light, moisture, and chemical contaminants. Storage in stable room conditions is crucial for preserving the integrity of the sample.

External references

Sources

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