Maleevite
Chemical formula: BaB₂Si₂O₈
Maleevite is a very rare barium-boron silicate, forming colorless, tabular crystals with a vitreous luster.
Properties
- Mohs hardness
- 7
- Color
- White
- Luster
- Vitreous
- Streak
- White
- Density
- 3.78
- Cleavage
- Perfect on {010}
- Fracture
- Irregular/Uneven
- Transparency
- Transparent
- Crystal system
- Orthorhombic
Diagnostic features
## Identification Identifying maleevite is extremely difficult without advanced analytical methods. Visually, it is characterized by the presence of very small, colorless, tabular crystals with a vitreous luster. Identification requires confirmation of its chemical composition (presence of barium, boron, and silicon) using methods such as EDS/WDS. ## Distinguishing from Similar Minerals It can be confused with other colorless, microscopic minerals found in the same environment, such as quartz, danburite, or reedmergnerite. Differentiation relies on crystallographic and chemical analysis. Its high density can be a helpful auxiliary feature. ## Crystal Forms Crystals are tabular or platy, often elongated. They crystallize in the orthorhombic system. They usually occur as single, disseminated crystals or small, loose aggregates.
Geological environment
## Genesis Maleevite forms in syenite pegmatites rich in quartz and microcline, which cut alkaline intrusions. It is a late-stage crystallization mineral in these specific geochemical conditions. ## Mineral Associations This mineral co-occurs with quartz, microcline, aegirine, reedmergnerite, leucophanite, polylithionite, and pekovite. It is found in paragenesis with other rare borosilicate minerals. ## Localities The only confirmed locality for maleevite in the world is its type locality – the Dara-i-Pioz glacier massif in the Alai Mountains, Tajikistan. This is one of the world's most famous sites for rare minerals.
Rarity
Extremely rare
For collectors
## Quality Criteria The quality of a maleevite specimen is determined by the size and development of the crystals, as well as their abundance on the rock matrix. The most desirable specimens are those with clearly visible, sharply terminated, transparent crystals, contrasting with the surrounding minerals. Due to the microscopic nature of the mineral, the quality of the specimen under magnification is crucial. ## Popular Localities The only source of collectible specimens is the Dara-i-Pioz massif in Tajikistan. Specimens from this locality are highly valued by collectors specializing in rare mineral species and "micromount" specimens.
Care and storage
## Cleaning Specimens should only be cleaned with compressed air to remove dust. Due to the microscopic size of the crystals and their fragility, any form of mechanical or chemical cleaning, including with water, is discouraged. ## What to Avoid Avoid contact with chemicals, ultrasound, and all forms of mechanical cleaning (brushes, cloths). The crystals are brittle and susceptible to mechanical damage. ## Storage Maleevite specimens should be stored in stable conditions, in sealed "micromount" boxes that protect them from dust, shocks, and mechanical damage. Avoid sudden temperature changes.