Vakhrushevaite

Chemical formula: Mg<sub>5</sub>Cr<sup>3+</sup>(AlSi<sub>3</sub>O<sub>10</sub>)(OH)<sub>8</sub>

Vakhrushevite is an extremely rare, green mineral from the chlorite group, a magnesium-chromium silicate.

## Characteristics Vakhrushevite is a mineral from the chlorite group, belonging to the layered silicates. It occurs as very fine, scaly crystals with a hexagonal outline, forming rosette-like or spherulitic aggregates. Its dimensions are microscopic, usually not exceeding 0.1 mm. It is a mineral with a characteristic, intensely green color. ## Physical properties Due to the microscopic size of the crystals, most physical properties are difficult to determine precisely. Hardness is estimated at approximately 2.5 on the Mohs scale. The mineral exhibits perfect cleavage in one direction, typical for platy minerals. The luster is vitreous. ## Colors and varieties This mineral occurs in one characteristic color - an intense, emerald green. No color varieties or commercial forms are known. ## History and name The mineral's name honors the Russian mineralogist Valentina Alexandrovna Vakhrusheva (1919-1998), a specialist in Ural deposits. It was approved as a new mineral species by the International Mineralogical Association (IMA) in 1999. It was first described by V.I. Ankinovich and co-authors.

Properties

Mohs hardness
2.5
Luster
Vitreous
Streak
Light green
Density
2.85
Cleavage
Perfect on {001}
Fracture
Uneven
Transparency
Translucent
Crystal system
Monoclinic

Diagnostic features

## Identification Field identification of vakhrushevite is practically impossible due to its microscopic size. Identification requires advanced laboratory methods, such as chemical analysis (EDS) and X-ray diffraction (XRD). A visual feature that may draw attention is the tiny, intensely green aggregates against a background of black shales. ## Distinguishing from similar minerals It can be confused with other green minerals from the chlorite group, such as clinochlore or chamosite, as well as with chromium mica - fuchsite. Definitive differentiation is only possible based on chemical composition analysis, confirming the simultaneous presence of magnesium and chromium in specific proportions. ## Crystal forms It forms microscopic, hexagonal plates and flakes, which combine into rosette-like, spherulitic, or spherical aggregates.

Geological environment

## Genesis Vakhrushevite forms as a result of low-grade metamorphic processes. It occurs in black carbonaceous-siliceous shales that have undergone potassic metasomatism. ## Mineral associations In the type locality (Urup deposit), it coexists with quartz, pyrite, sphalerite, galena, chalcopyrite, tetrahedrite, rutile, anatase, monazite-(Ce), xenotime-(Y), and minerals from the chlorite group. ## Localities The only confirmed and described occurrence of this mineral in the world is the Urup copper and pyrite deposit in the northern part of the Caucasus in Russia.

Rarity

Extremely rare

For collectors

## Quality criteria As a "micromount" type mineral, its collector value depends on the richness and aesthetics of the aggregates on the rock matrix. Most valued are specimens with clearly formed, intensely green rosettes or spherulites, contrasting well with the dark background of the host rock. The size of the aggregates, although still microscopic, is also important. ## Popular localities All specimens available on the collector's market come from a single locality - the Urup deposit in Russia.

Care and storage

## Cleaning Vakhrushevite specimens are extremely small and delicate, usually occurring on the host rock. Mechanical or chemical cleaning is not recommended. The safest way to remove dust is with compressed air from a safe distance. ## What to avoid Avoid contact with all chemicals, acids, and detergents. Due to its low hardness, the mineral is very susceptible to mechanical damage. It should be protected from abrasion and scratching. ## Storage Specimens should be stored in stable conditions, in enclosed "micromount" boxes, to protect them from dust and mechanical damage. They do not require special protection from light or humidity, but stability is key.

Sources

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