Vlodavetsite

Chemical formula: Ca<sub>2</sub>Al(S<sup>6+</sup>O<sub>4</sub>)<sub>2</sub>F<sub>2</sub>Cl·4H<sub>2</sub>O

An extremely rare sulfate mineral, forming colorless or white, platy microcrystals in volcanic exhalation products.

## Characteristics Wlodavetsite is a very rare, hydrated aluminum, calcium, fluorine, and chlorine sulfate. It occurs as very small, thin, platy crystals with a square outline, usually not exceeding fractions of a millimeter. These crystals often form subtle coatings, crusts, or fan-shaped aggregates on volcanic rocks. Due to the microscopic size of the crystals, it is a mineral almost exclusively for micromineralogy collectors. ## Physical Properties This mineral is very soft, with a Mohs hardness of about 2-2.5, meaning it can be scratched with a fingernail. It has a vitreous luster and is transparent to translucent. Its density is low, approximately 2.43 g/cm³. ## Colors and Varieties Wlodavetsite is typically colorless or white. No colored varieties or trade names are known. ## History and Name The mineral was approved by the IMA in 1993. Its name honors Vladimir Ivanovich Wlodavets (1893-1993), a prominent Russian volcanologist and petrographer, researcher of Kamchatka volcanoes. The discovery was made on material from fumarolic products of the Great Fissure Eruption of Tolbachik volcano in Kamchatka, Russia, which is its type locality. ## Uses Wlodavetsite has no industrial applications. It is solely an object of scientific and collecting interest.

Properties

Mohs hardness
2-2.5
Luster
Vitreous
Streak
White
Density
2.43
Cleavage
Perfect on {001}
Fracture
Stepped
Transparency
Transparent to Translucent
Crystal system
Tetragonal

Diagnostic features

## Identification Identification of wlodavetsite under amateur conditions is practically impossible. Key features include its unique occurrence environment (active volcanic fumaroles), microscopic size, thin-platy crystal habit with a square cross-section, and co-occurrence with other rare exhalative minerals. Certain identification requires advanced analytical methods such as X-ray diffraction (XRD) and chemical microanalysis (EDS). ## Distinguishing from similar minerals It can be confused with other white or colorless fumarole products, such as gypsum, anhydrite, or creedite. It is distinguished from gypsum by its tetragonal crystal form (gypsum is monoclinic). Differentiation from other rare sulfates and fluorides requires specialized equipment. ## Crystal Forms It forms very thin, platy crystals with a square habit, consistent with tetragonal symmetry. Crystals often arrange into parallel intergrowths, rosette-like or fan-shaped aggregates, and also form thin crusts and coatings.

Geological environment

## Genesis Wlodavetsite is a fumarolic mineral. It forms by sublimation from hot volcanic gases (exhalations) at temperatures of about 100-150°C. It crystallizes directly on the surface of volcanic rocks near fumarole vents. ## Mineral Associations This mineral co-occurs with other products of volcanic exhalations. At the type locality on Tolbachik volcano, these include gypsum, anhydrite, jarosite, creedite, ralstonite, gearksutite, and other rare sulfates and fluorides. ## Localities It is an extremely rare mineral, known from only a few localities worldwide. The most important and historical occurrence, from which the best specimens originate, is the area of the Great Fissure Eruption of Tolbachik volcano on the Kamchatka Peninsula in Russia.

Rarity

Extremely rare

For collectors

## Quality Criteria The quality of wlodavetsite specimens, being a micromineralogical mineral, is assessed by different criteria than for macroscopic specimens. Samples with rich, dense clusters of well-formed, sharp microcrystals are most highly valued. The aesthetics of the matrix and the presence of rare associated minerals, which enhance the scientific and collecting value of the specimen, are also important. ## Popular Localities The only source of collectible specimens is its type locality - Tolbachik volcano in Kamchatka, Russia. Specimens from this location are the standard for this mineral.

Care and storage

## Cleaning Wlodavetsite specimens are extremely delicate and sensitive to moisture. Only compressed air (with great caution) or a very soft, dry brush should be used for cleaning to remove dust. Absolutely avoid contact with water and other liquids. ## What to avoid The mineral is partially soluble in water. It must be protected from moisture, water, chemicals, and acids. It is also very soft and brittle, so shocks, impacts, and friction should be avoided. ## Storage It is recommended to store specimens exclusively in sealed "micromount" containers, which protect the mineral from atmospheric moisture, dust, and mechanical damage. Avoid exposure in damp rooms.

Sources

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