Telyushenkoite

Chemical formula: CsNa₆Be₂Al₃Si₁₅O₃₉F₂

Telyushenkoite is a very rare mineral from the leifite group, a transparent cesium, sodium, beryllium, and aluminum silicate, found in Tajikistan.

## Characteristics Telyushenkoite is an extremely rare mineral belonging to the leifite group. It forms colorless or white, hexagonal, prismatic crystals, which can reach up to 2 cm in length and 0.5 cm in width. Crystals are typically transparent and exhibit a vitreous luster. They often occur as radial aggregates or single, well-formed columns. ## Physical Properties This mineral is characterized by a Mohs hardness of 6, comparable to that of feldspars. Its density is approximately 2.73 g/cm³. It is transparent, and its luster is described as vitreous. The streak is white. ## Colors and Varieties Telyushenkoite occurs in a limited range of colors, from completely colorless to white. No colored or commercial varieties have been distinguished. ## History and Name The mineral is named in honor of Tamara Leonidovna Telyushenko (1936-1996), a Russian mineralogist and geochemist from the Institute of Mineralogy, Geochemistry and Crystal Chemistry of Rare Elements (IMGRE) in Moscow. It was approved as a new mineral species by the IMA in 2001, and its discovery was made in the Dara-i-Pioz massif in Tajikistan. ## Uses Due to its extreme rarity, telyushenkoite has no industrial applications. It is solely an object of scientific interest and a valuable acquisition for specialized collectors of rare minerals.

Properties

Mohs hardness
6
Luster
Vitreous
Streak
White
Density
2.73
Transparency
Transparent
Crystal system
Trigonal

Diagnostic features

## Identification A characteristic feature of telyushenkoite is its habit – hexagonal, prismatic crystals, often grouped into radial aggregates. Colorless or white color, vitreous luster, and a Mohs hardness of 6 are key identifying features. However, definitive confirmation requires advanced analytical methods due to its similarity to other minerals. ## Distinguishing from Similar Minerals Telyushenkoite can be confused with other minerals from the leifite group, such as leifite or eirikite, from which it differs mainly in chemical composition (cesium dominance). It may also resemble some forms of quartz, beryl, or tourmaline (colorless varieties), but it differs from them in crystallographic system, hardness, and other physical properties. ## Crystal Forms This mineral forms well-developed, elongated prismatic crystals with a hexagonal cross-section. Crystals often occur as radial or stellate aggregates, embedded in the host rock.

Geological environment

## Genesis Telyushenkoite forms under specific geological conditions, within alkaline-rich syenite pegmatites. Its occurrence is associated with metasomatic processes in the final stages of magma crystallization. ## Mineral Associations This mineral co-occurs with other rare pegmatitic minerals. At the type locality (Dara-i-Pioz), it was found in association with quartz, microcline, aegirine, polylithionite, leucophanite, reedmergnerite, and other minerals from the leifite group. ## Localities The only confirmed and thoroughly described occurrence of telyushenkoite in the world is its type locality – the Dara-i-Pioz glacier in the Alai Mountains, Tajikistan. This region is known for the occurrence of many unique and rare minerals.

Rarity

Very rare

For collectors

## Quality Criteria The most highly valued telyushenkoite specimens are those with well-formed, sharp, transparent, and undamaged crystals. Radial aggregates with clearly visible, individual crystals, embedded in a contrasting rock matrix, are particularly desirable. Crystal size is also a key factor – specimens with crystals exceeding 1 cm are considered exceptional. ## Popular Localities As this mineral is known from only one location in the world, all collectible specimens originate from the Dara-i-Pioz massif in Tajikistan. This is the sole source for obtaining this mineral.

Care and storage

## Cleaning Telyushenkoite specimens should be cleaned very carefully, using a soft brush to remove dust. If necessary, distilled water can be used, but prolonged soaking should be avoided. Always allow the specimen to dry completely at room temperature. ## What to Avoid Avoid contact with chemicals, especially acids and strong detergents, which can damage the crystal surface. The mineral is sensitive to rapid temperature changes and should not be exposed to ultrasonic cleaners. ## Storage Collectible telyushenkoite specimens, being extremely rare and valuable, should be stored in separate, padded boxes (such as "perky boxes") to prevent scratches and mechanical damage. They should be protected from dust and direct, prolonged exposure to sunlight.

External references

Sources

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