Vladkrivovichevite

Chemical formula: [Pb₂+₃₂O₁₈][Pb₂+₄Mn₂+₂O]Cl₁₄(BO₃)₈·₂H₂O

A very rare lead oxychloride borate, known for its complex structure and occurrence as microscopic, tabular crystals in volcanic fumaroles.

## Characteristics Vladkrivovichevite is a complex lead and manganese oxychloride borate. It forms very small, thin, tabular crystals with a square or octagonal outline, flattened in one plane. They reach a size of up to 0.4 mm. Crystals often intergrow into parallel packets or form attractive, radial aggregates resembling rosettes. The mineral is characterized by an intense, adamantine luster. ## Physical Properties It is a transparent mineral with a high density of approximately 7.55 g/cm³. Hardness has not been determined due to the small size and fragility of the crystals. It exhibits perfect cleavage in one plane, perpendicular to the longest crystal axis. ## Colors and Varieties Vladkrivovichevite occurs in shades from yellow, through orange-yellow, to reddish-orange. No varieties have been distinguished. ## History and Name The mineral is named in honor of Vladislav V. Krivovichev (born 1970), a Russian mineralogist and crystallographer, professor at St. Petersburg University, specializing in the mineralogy and crystal chemistry of oxygen minerals. It was approved as a new mineral species by the International Mineralogical Association (IMA) in 2014. The scientific description was published in 2015. ## Uses Due to its extreme rarity and microscopic size, vladkrivovichevite has no practical applications. It is solely an object of scientific research and a valuable acquisition for specialized micromineral collectors.

Properties

Luster: Adamantine
Streak: Light yellow
Density: 7.55
Cleavage: Perfect on {001}
Transparency: Transparent
Crystal system: Tetragonal

Diagnostic features

## Identification Identification of vladkrivovichevite is based on its characteristic form – thin, tabular crystals, often forming rosettes. The intense, adamantine luster, yellow-orange color, and specific occurrence environment (volcanic fumaroles) are also helpful. A pale yellow streak is an additional diagnostic feature. ## Distinguishing from Similar Minerals It can be confused with other rare, yellow minerals from the fumaroles of Tolbachik volcano, such as sophiite or ilinskite. Due to its microscopic size and similar appearance, definitive differentiation is almost exclusively possible using advanced analytical methods, such as X-ray microanalysis (EDS/WDS) or X-ray diffraction (XRD). ## Crystal Forms Crystals are thin, tabular, flattened parallel to the basal plane {001}. They can be square or octagonal in outline. They occur as single flakes, parallel intergrown packets, or as radial aggregates (rosettes) up to 0.6 mm in diameter.

Geological environment

## Genesis Vladkrivovichevite is a fumarolic mineral. It forms by sublimation, crystallizing directly from hot volcanic gases rich in lead, chlorine, and boron, at temperatures above 450-500°C. ## Mineral Associations This mineral coexists with other volcanic exhalation products, such as cotunnite, anglesite, tenorite, hematite, sophiite, ilinskite, and newly discovered borates, such as anhydroboroleacite. ## Localities The only known occurrence of vladkrivovichevite in the world is its type locality – the Yadovitaya fumarole on the second cinder cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption on Tolbachik volcano (Kamchatka, Far East, Russia).

Rarity

Extremely rare

For collectors

## Quality Criteria The quality of specimens of this micromineral is assessed based on several criteria. The most highly valued are well-formed, sharp, and undamaged crystals forming aesthetic, radial aggregates (rosettes). The intensity and attractiveness of the color are also important. Specimens with a rich association of other rare fumarolic minerals are particularly desirable. ## Popular Localities The only source of specimens is the difficult-to-access type locality on Tolbachik volcano in Kamchatka. For this reason, specimens are almost exclusively available in specialized circles, among scientific institutions and advanced micromineral collectors.

Care and storage

## Cleaning Vladkrivovichevite specimens are extremely small and delicate. Any mechanical cleaning (e.g., with a brush) or chemical cleaning is absolutely inadvisable and risks irreversible damage to the crystals. Fine dust can only be removed with a very gentle stream of air from a rubber bulb. ## What to Avoid Avoid contact with water and all chemicals, as it is a chloride and may react. The mineral is likely sensitive to changes in temperature and humidity. Protect it from direct sunlight, which can cause fading. ## Storage Specimens should only be stored in specialized "micromount" boxes, which protect them from dust, shocks, and humidity changes. Display should be in stable conditions, away from sources of vibration and heat.

Sources

IMA Mineral List (CNMNC)