Pollucite Mineral Overview

• Mineral name: Pollucite
• Mineral class: Silicate (tectosilicate)
• Chemical formula: (Cs,Na)₂Al₂Si₄O₁₂·2H₂O
• Crystal system: Isometric (cubic)
• Mohs hardness: 6–6.5
• Color range: Colorless, white, gray, pale pink
• Luster: Vitreous
• Streak: White
• Cleavage: Poor
• Fracture: Conchoidal to uneven
• Specific gravity: Approximately 2.9–3.0
• Transparency: Transparent to translucent
• Common locations: Canada, United States, Afghanistan, Brazil, Namibia
• Uses: Major ore of cesium
• Similar minerals: Quartz, analcime, feldspar

Naming and Classification

Pollucite is a cesium-rich silicate mineral, named after Pollux, one of the twin brothers (Castor and Pollux) from Greek mythology. Its counterpart in naming is:

• Castorite (an old name sometimes used for petalite)

Pollucite is one of the primary natural sources of cesium, a rare alkali metal.

Physical and Optical Characteristics

Pollucite typically occurs as:

• Massive or granular material
• Rare cubic crystals

It is usually colorless to white, sometimes with:

• Pale gray or pinkish tones

Its appearance can resemble quartz or feldspar, but it often has a slightly more cloudy or milky look.

The luster is vitreous, and with a hardness of 6–6.5, it is moderately durable.

Chemical Composition and Structure

Pollucite is composed of:

• Cesium (Cs)
• Sodium (Na)
• Aluminum (Al)
• Silicon (Si)
• Water (H₂O)

It has a three-dimensional framework (tectosilicate structure) similar to zeolites, with:

• Large cavities that accommodate cesium ions
• Channels that can contain water molecules

This structure is key to its role as a cesium host mineral.

Formation and Geological Occurrence

Pollucite forms in rare-element granitic pegmatites, particularly in:

• Lithium- and cesium-rich environments
• Late-stage crystallization zones

Typical formation conditions include:

• Highly evolved magma
• Concentration of rare alkali elements

It is commonly associated with:

• Lepidolite
• Spodumene
• Petalite
• Quartz

These associations are typical of lithium-cesium pegmatite systems.

Common Locations

Pollucite is found in several important pegmatite regions:

• Canada: Manitoba (major cesium source)
• United States: Maine and other pegmatite مناطق
• Afghanistan: Gem-bearing pegmatites
• Brazil and Namibia: Rare-element deposits

Canadian deposits are especially significant for industrial extraction.

Uses and Practical Significance

Pollucite is extremely important economically:

Cesium Production

• Primary ore of cesium, used in:
  • Atomic clocks
  • Drilling fluids
  • Electronics and scientific equipment

Scientific Applications

• Cesium is critical for:
  • Time measurement standards
  • Specialized الكيمياء and research

Collector Mineral

• Transparent specimens may be faceted (rare)
• Massive material collected for mineralogical interest

Similar and Related Minerals

Pollucite can resemble:

• Quartz: Harder and lacks internal water structure
• Analcime: Similar structure but different composition
• Feldspar: Different cleavage and composition

Chemical analysis is often needed for precise identification.

Identification Notes for Collectors

• Look for colorless to milky material in pegmatites
• Note moderate hardness (6–6.5)
• Observe lack of strong cleavage
• Consider association with lithium and cesium minerals
• Confirm with testing due to similarity to quartz

Pollucite is a cesium-rich silicate mineral, recognized for its importance as the primary source of cesium and its occurrence in rare-element pegmatites, making it both industrially significant and of interest to collectors.