Dzhuluite

Chemical formula: Ca₃(Sn⁴⁺Sb⁵⁺)Fe³⁺₃O₁₂

Dzhuluite is a rare garnet group mineral, a complex oxide of calcium, tin, antimony, and iron, found in skarns.

## Characteristics Dzhuluite is a rare mineral belonging to the garnet supergroup, specifically to the bitikleite group. It forms small, single, isometric crystals, reaching up to 0.3 mm in size. It typically occurs as grains embedded in other minerals. Its name refers to the historical name of the discovery locality. ## Physical Properties Dzhuluite crystals exhibit a strong, metallic luster. The mineral is opaque and black in color. Its Mohs hardness is approximately 6, and its calculated density is 4.83 g/cm³. It is brittle and shows no cleavage. ## Colors and Varieties Dzhuluite is an idiochromatic mineral, meaning its black color results directly from its chemical composition, mainly due to the presence of iron. No color varieties or commercial varieties are distinguished. ## History and Name The mineral was approved by the IMA in 2010 (IMA2010-011). Its name comes from the historical name of Mount Dzhulu in Kabardino-Balkaria, where the type locality is situated. It was described by a team of mineralogists led by Irina O. Galuskina. ## Applications Due to its extreme rarity and microscopic crystal size, dzhuluite has no commercial or industrial applications. It is solely an object of scientific interest and a collector's item for specialized rare mineral collectors.

Properties

Mohs hardness
6
Color
Light-yellow to dark-brown
Luster
Metallic
Streak
Creamy
Density
4.708
Cleavage
None
Fracture
Uneven
Transparency
Opaque
Crystal system
Isometric

Diagnostic features

## Identification Identification of dzhuluite is impossible without advanced analytical techniques. Identification requires chemical analysis (e.g., using an electron microprobe) and structural studies (X-ray diffraction). In collector's conditions, it can only be identified based on a label from a confirmed source. ## Distinguishing from Similar Minerals It can be confused with other black, metallic-lustered garnet group minerals, such as schorlomite, kimzeyite, or other oxides (e.g., magnetite, franklinite). Visual distinction is unfeasible; analysis of composition is necessary, especially to confirm the simultaneous presence of tin and antimony. ## Crystal Forms Dzhuluite crystallizes in the isometric system, forming crystals with a rhombic dodecahedral habit {110}, sometimes in combination with trapezohedral faces {211}. It occurs as single, well-formed, isometric crystals.

Geological environment

## Genesis Dzhuluite forms as a result of metasomatic processes in contact zones, within calc-silicate skarns. Its crystallization is associated with high-temperature (600–650°C) and low-pressure conditions of contact metamorphism, at the contact of a syenite intrusion with carbonate sediments. ## Mineral Associations This mineral coexists with other minerals typical of the skarn environment. At the type locality, it was found in association with calcite, fluorite, andradite, kimzeyite, kerimasite, larnite, rondorfite, as well as minerals from the ettringite group (e.g., thaumasite). ## Localities The only confirmed occurrence of dzhuluite in the world is its type locality - Bitchuu skarn, in the upper reaches of the Cheget River, in Kabardino-Balkaria, Russia.

Rarity

Extremely rare

For collectors

## Quality Criteria The quality of a dzhuluite specimen is determined by the size and quality of crystal development, although even the largest do not exceed a fraction of a millimeter. The most desirable specimens are those with sharp, lustrous, fully formed crystals, clearly visible against a contrasting matrix (e.g., on calcite). The richness of association with other rare minerals is also important. ## Popular Localities All known specimens come from a single location in the world - the Bitchuu skarn in Russia. This makes it an extremely difficult mineral to acquire, and its availability on the collector's market is negligible.

Care and storage

## Cleaning Specimens of dzhuluite, due to the microscopic size of the crystals and their brittleness, should not be mechanically cleaned. Any procedures may damage the delicate crystals. If dust removal is necessary, compressed air can be used from a safe distance. ## What to Avoid Avoid contact with chemicals, especially acids, which can react with the mineral or the host rock. Also, avoid ultrasound and sudden temperature changes. ## Storage Specimens should be stored under stable conditions, in a closed "micromount" box, to protect them from dust and mechanical damage. It is not sensitive to light, but protection from physical factors is crucial.

External references

Sources

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