Odigitriaite
Chemical formula: CsNa₅Ca₅[Si₁₄B₂O₃₈]F₂
Odygitriait is an extremely rare mineral from the silicate group, distinguished by its complex chemical composition with cesium and boron, and its unique purple color.
Properties
- Mohs hardness
- 5
- Color
- colorless
- Luster
- Vitreous
- Streak
- white
- Density
- 2.80
- Cleavage
- {001}
- Fracture
- Irregular/Uneven
- Transparency
- Translucent
- Crystal system
- Monoclinic
Diagnostic features
## Identification Identification of odygitriait is primarily based on its unique physical characteristics and location. Key features include its intense purple color, vitreous luster, and occurrence as small grains in a specific geological environment (agpaitic pegmatites). Final identification requires advanced analytical methods such as Raman spectroscopy or chemical analysis (EDS/WDS). ## Distinguishing from Similar Minerals Odygitriait can be confused with other purple minerals found in the Khibiny Massif, such as fluorite or some eudialytes. It is distinguished from them by its hardness (higher than fluorite) and its specific co-occurrence with minerals such as tinaksite or delhayelite. Unlike eudialyte, it does not decompose in acids. ## Crystal Forms This mineral forms anhedral (irregular) grains up to 2 mm in size, occurring in aggregates or as individual inclusions in other minerals, mainly in tinaksite.
Geological environment
## Genesis Odygitriait forms under very specific conditions, within agpaitic pegmatites, which are highly enriched in alkalis (sodium, potassium) and rare elements. Its crystallization is associated with the late stages of nepheline syenite magma evolution in the Khibiny Massif. ## Mineral Associations This mineral occurs in close association with tinaksite (often as inclusions within it), delhayelite, arfvedsonite, aegirine, microcline, nepheline, sodalite, eudialyte, lorenzenite, lamprophyllite, and villiaumite. ## Localities The only confirmed locality for odygitriait in the world is its type locality: Mount Koashva in the Khibiny Massif, on the Kola Peninsula in the Murmansk Oblast, Russia.
Rarity
Extremely rare
For collectors
## Quality Criteria The quality of an odygitriait specimen primarily depends on the intensity and saturation of the purple color of the grains and their size. The most desirable specimens are those where odygitriait grains are clearly visible, contrast with the surrounding matrix (e.g., with brightly colored tinaksite), and form rich aggregates. Since the mineral does not form well-developed crystals, form is not a criterion for evaluation. ## Popular Localities The only source of specimens is Mount Koashva in Russia. Material from this locality is highly valued by collectors specializing in rare and systematic minerals.
Care and storage
## Cleaning Due to its extreme rarity and small grain size, odygitriait specimens practically do not require cleaning. If necessary, compressed air can be used to remove dust. Avoid contact with water and chemicals. ## What to Avoid Protect the mineral from all chemicals, acids, and detergents. Due to its rarity, it should not be exposed to ultrasound or high temperatures. Avoid scratches and impacts. ## Storage Odygitriait specimens should be stored in stable conditions, in sealed "micromount" boxes, to protect them from dust, moisture, and mechanical damage. Avoid exposure to direct sunlight, although its effect on color has not been fully studied.