Bafertisite
Bafertisite Mineral Overview
Mineral name: Bafertisite
Mineral class: Silicate (phyllosilicate)
Known Facts
- Chemical formula: BaFe²⁺₂Ti₂Si₄O₁₄(OH)₂ (may vary slightly)
- Crystal system: Monoclinic
- Mohs hardness: 3–4
- Color range: Brown, dark brown, reddish-brown
- Luster: Vitreous to pearly
- Streak: Light brown
- Cleavage: Perfect in one direction
- Fracture: Uneven
- Specific gravity: Approximately 3.5–3.7
- Common locations: Russia (Kola Peninsula), Greenland
- Uses: Collector specimens, scientific study
- Similar minerals: Astrophyllite, annite, other iron-rich phyllosilicates
Physical and Optical Characteristics
Bafertisite typically occurs as:
- Platy or lamellar crystals
- Foliated or micaceous aggregates
- Thin sheets or flakes
It is usually translucent to opaque, with colors ranging from brown to dark reddish-brown.
The luster is vitreous, often becoming pearly on cleavage surfaces, reflecting its layered structure.
A defining feature is its perfect cleavage, allowing it to split into thin, flexible or brittle sheets.
Chemical Composition and Structure
Bafertisite has the formula:
- BaFe²⁺₂Ti₂Si₄O₁₄(OH)₂
It is a barium–iron–titanium silicate, containing:
- Barium (Ba)
- Iron (Fe²⁺)
- Titanium (Ti)
- Silicate sheets (Si₄O₁₄ units)
- Hydroxyl (OH)
It belongs to a group of layered silicates (phyllosilicates), characterized by:
- Sheet-like structures
- Strong cleavage parallel to the layers
The presence of titanium and barium distinguishes it from more common mica-group minerals.
Formation and Geological Occurrence
Bafertisite forms in alkaline igneous environments, particularly:
- Nepheline syenites
- Alkaline intrusive complexes
Typical formation conditions include:
- Crystallization in silica-poor, alkali-rich systems
- Late-stage formation in iron- and titanium-rich environments
It is commonly associated with:
- Astrophyllite
- Aegirine
- Nepheline
- Sodalite
These assemblages are characteristic of rare-element alkaline complexes.
Common Locations
Notable occurrences of Bafertisite include:
- Russia: Kola Peninsula (major source)
- Greenland: Ilímaussaq complex
These regions are well known for rare and unusual silicate minerals.
Uses and Practical Significance
Bafertisite has no industrial applications. Its importance lies in:
- Mineral collecting: Due to rarity and association with unusual minerals
- Scientific study: Particularly in alkaline rock mineralogy and titanium-bearing silicates
Similar and Related Minerals
Bafertisite may be confused with:
- Astrophyllite: Similar color and habit but typically more bronzy and radiating
- Annite (mica): Also brown and platy but lacks titanium-rich composition
- Other iron-rich phyllosilicates
Distinguishing features include:
- Presence of barium and titanium
- Occurrence in alkaline complexes
- Platy, micaceous habit with perfect cleavage
Identification Notes for Collectors
- Look for brown, platy crystals in alkaline igneous rocks
- Note association with astrophyllite and aegirine
- Check for perfect cleavage and micaceous habit
- Observe vitreous to pearly luster
- Use analytical methods to confirm due to similarity with other sheet silicates
Bafertisite is a rare barium–iron–titanium phyllosilicate, recognized for its layered structure and occurrence in alkaline igneous complexes, and is primarily of interest to collectors and mineralogists studying rare-element silicate systems.