Filatovite

Chemical formula: K(Al,Zn²⁺)₂(As⁵⁺,Si)₂O₈

Filatovite is a rare potassium aluminum arsenate from the feldspar group, notable for being the arsenate analog of microcline.

## Characteristics Filatovite is an arsenate mineral from the feldspar group, chemically classified as a potassium, aluminum, and zinc arsenate. It is the arsenate analog of microcline. It forms very small, colorless, tabular crystals, usually not exceeding 0.1 mm, which occur as aggregates or crusts on other minerals. Due to the microscopic size of the crystals, its visual features are difficult to assess without specialized equipment. ## Physical Properties Filatovite crystals exhibit a vitreous luster. Its Mohs hardness is 5-6. It is a transparent mineral. The calculated density is approximately 3.23 g/cm³. ## Colors and Varieties Filatovite is a colorless mineral. No colored or commercial varieties have been identified. ## History and Name The mineral was named in honor of Professor Stanislav Konstantinovich Filatov (born 1940), a crystallographer from Saint Petersburg State University in Russia, for his contributions to mineralogy and crystal chemistry. It was first discovered and described in fumarole products of the Tolbachik volcano in Kamchatka, Russia. ## Uses Filatovite has no industrial application. Its significance is purely scientific and collectible, as a unique member of the feldspar group.

Properties

Mohs hardness: 5-6
Color: colourless
Luster: Vitreous
Streak: White
Density: 0
Cleavage: on {100}
Fracture: Uneven
Transparency: Transparent
Crystal system: Monoclinic

Diagnostic features

## Identification Identification of filatovite is only possible using advanced analytical methods, such as X-ray diffraction (XRD) and chemical microanalysis (EDS/WDS). Visual identification in the field or even in a collection is impossible due to the microscopic size of the crystals and the lack of characteristic macroscopic features. ## Distinguishing from Similar Minerals Filatovite is the arsenate analog of microcline. Distinguishing it from other microscopic, colorless minerals found in fumarolic environments (e.g., other arsenates, silicates) requires specialized research equipment. ## Crystal Forms Filatovite forms very small, tabular crystals with a habit typical of feldspars. They occur as single, isolated crystals or, more commonly, as fine-grained aggregates and crusts.

Geological environment

## Genesis Filatovite is a mineral of volcanic origin, formed by sublimation from volcanic gases in high-temperature fumaroles. It crystallizes in an environment rich in arsenic, potassium, and aluminum. ## Mineral Associations This mineral coexists with other rare arsenates and fumarolic minerals, such as johillerite, arsenatrotitanite, lammerite, tenorite, hematite, aphthitalite, and langbeinite. ## Localities The only confirmed occurrence of filatovite in the world is its type locality – the fumaroles of the Second Northern Cone of the Great Fissure Eruption of Tolbachik volcano in Kamchatka, Russia.

Rarity

Extremely rare

For collectors

## Quality Criteria The quality of filatovite specimens is primarily assessed based on the richness and quantity of crystals on the rock matrix, as well as their association with other rare minerals from that locality. Due to their microscopic nature, individual crystals have no collector's value – rich aggregates visible under magnification are what count. ## Popular Localities The only source of filatovite specimens is the Tolbachik volcano in Kamchatka. Specimens from this locality are highly prized by collectors specializing in rare minerals and "micromounts."

Care and storage

## Cleaning Due to the extreme rarity and microscopic size of the crystals, filatovite specimens should not be cleaned mechanically or chemically. Any attempts at cleaning may destroy the delicate crystals. It is recommended to only remove dust using compressed air from a safe distance. ## What to Avoid Avoid contact with all chemicals, acids, and bases. The mineral is sensitive to shocks and temperature changes. It should not be cleaned in ultrasonic cleaners. Protect it from moisture and direct sunlight. ## Storage Filatovite specimens should be stored in stable conditions, preferably in closed, padded "micromount" boxes that protect them from dust, mechanical damage, and humidity changes. Display should be in a secured display case.

External references

https://www.mindat.org/min-26577.html