Zeravshanite

Chemical formula: Na<sub>2</sub>Cs<sub>4</sub>Zr<sup>4+</sup><sub>3</sub>Si<sub>18</sub>O<sub>45</sub>·2H<sub>2</sub>O

Zeravshanite is an extremely rare zirconium, cesium, and sodium silicate, forming colorless, tabular crystals with a hexagonal outline.

## Characteristics Zeravshanite is a very rare mineral from the silicate group, belonging to the zektzerite group. It occurs as small, colorless, tabular crystals with a hexagonal outline, reaching sizes up to 0.3 mm. The crystals are usually transparent and exhibit a vitreous luster. ## Physical Properties The mineral is characterized by a hardness of approximately 6 on the Mohs scale. Its density is about 3.45 g/cm³. It is transparent, with a white streak and vitreous luster. It does not exhibit fluorescence under ultraviolet light. ## History and Name The mineral's name comes from its discovery locality – the Dara-i-Pioz glacier in the Zeravshan Mountains (part of the Alai-Pamir system) in Tajikistan. It was first described in 2003 by A. Agakhanov and co-workers, and approved by the International Mineralogical Association (IMA) in the same year (IMA2003-030). ## Applications Due to its extreme rarity and microscopic crystal sizes, zeravshanite has no industrial or commercial applications. Its significance is purely scientific and it is an object of interest for specialized collectors of rare minerals.

Properties

Mohs hardness
6
Luster
Vitreous
Streak
White
Density
3.45
Cleavage
Perfect on {0001}
Fracture
Uneven
Transparency
Transparent
Crystal system
Hexagonal

Diagnostic features

## Identification Identification of zeravshanite is possible only through advanced analytical methods, such as X-ray diffraction (XRD) and chemical analysis (EDS/WDS). Visually, on a macroscopic scale, it is impossible to identify. ## Differentiation from Similar Minerals It can be confused with other colorless minerals from the zektzerite group, such as tuvaite or olovorossite, as well as with quartz or albite, which often co-occur in the same rock. Differentiation requires specialized laboratory tests to determine the chemical composition (high cesium and zirconium content) and crystallographic parameters. ## Crystal Forms It forms hexagonal, tabular crystals, often flattened parallel to the {0001} plane. It occurs as single, isolated crystals within the host rock.

Geological environment

## Genesis Zeravshanite forms under very specific geological conditions. It occurs in agpaitic pegmatites, which are extremely saturated with alkaline elements (sodium, potassium, cesium) and rare elements. Its type locality is pegmatite veins within nepheline syenites. ## Mineral Associations This mineral co-occurs with a rich assemblage of other rare minerals. At the type locality, its association with microcline, quartz, aegirine, polylithionite, reedmergnerite, neptunite, as well as other cesium minerals like tuvaite and olovorossite, has been noted. ## Localities The only confirmed and described occurrence of zeravshanite in the world is its type locality: the Dara-i-Pioz glacier in the Alai Mountains, Tajikistan. This is one of the world's most famous localities for rare minerals.

Rarity

Extremely rare

For collectors

## Quality Criteria As a micromineral, the collector's value of zeravshanite primarily depends on the quality and size of the crystals visible under a microscope. The most desirable specimens are those with well-formed, sharp, undamaged crystals that are clearly isolated on the rock matrix. Contrast with surrounding minerals also enhances the aesthetic appeal of the specimen. The certainty of identification, confirmed by a reputable seller or analysis, is also crucial. ## Popular Localities The only source of collector specimens is the Dara-i-Pioz massif in Tajikistan.

Care and storage

## Cleaning Due to the microscopic size of the crystals and their embedding in the host rock, mechanical cleaning is neither recommended nor possible without specialized equipment. Specimens should be protected from dust. ## What to Avoid Avoid contact with chemicals, acids, and strong detergents. Do not subject the specimen to ultrasound. Protect from extreme temperature changes and direct, prolonged exposure to sunlight. ## Storage Zeravshanite specimens, as microminerals, should be stored in specialized "micromount" boxes that protect them from mechanical damage and dust. Avoid storage in areas with high humidity.

Sources

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