Parauranophane & Uranophane - Madawaska (Faraday) Mine, Faraday Township, Hastings County, Ontario, Canada

  Ca(UO₂)₂(SiO₃OH)₂ · 5H₂O                                   

Parauranophane and Uranophane: Faraday Mine, Ontario

The Faraday Mine, near Bancroft, Ontario, is a historically significant uranium mining site within the Grenville geological province. This area is well-known for its diverse mineralogy, including the presence of secondary uranium minerals such as uranophane and parauranophane. These minerals are closely related in composition and often occur together in uranium-rich oxidized zones.

Uranophane

• Chemical Formula: $Ca(U{O}_2{)}_2(Si{O}_{3}OH{)}_2\cdot 5H_{2}O$
• Crystal System: Monoclinic.
• Appearance:
  • Yellow to greenish-yellow in color.
  • Typically forms acicular (needle-like) or fibrous crystals, often in aggregates.
  • May display a silky or vitreous luster.
• Formation:
  • Forms in oxidized environments from the alteration of primary uranium minerals such as uraninite.
  • Commonly found in association with water-rich zones that allow uranium to dissolve and reprecipitate.
• Occurrence in Faraday Mine:
  • Found as secondary mineralization in the mine's oxidized uranium zones.
  • Associated with other secondary uranium minerals and silicates.

Parauranophane

• Chemical Formula: $Ca(U{O}_2{)}_2(Si{O}_{3}OH{)}_2\cdot 5H_{2}O$
• Crystal System: Orthorhombic.
• Appearance:
  • Similar in color to uranophane (yellow to greenish-yellow).
  • Crystals are typically prismatic or fibrous, resembling uranophane but with slight structural differences.
• Formation:
  • A polymorph of uranophane, meaning it shares the same chemical composition but crystallizes in a different structure.
  • Occurs under similar environmental conditions as uranophane but may form in slightly varied geochemical conditions.
• Occurrence in Faraday Mine:
  • Found alongside uranophane in oxidized zones of uranium deposits.
  • Typically coexists with other uranium-bearing secondary minerals.

Differences Between Uranophane and Parauranophane

1. Crystal Structure:
   • Uranophane: Monoclinic.
   • Parauranophane: Orthorhombic.
2. Formation:
   • Both form under similar conditions, but their structural differences reflect slight variations in their crystallization environments.
3. Rarity:
   • Parauranophane is generally less common than uranophane and can be considered a rarer polymorph.

Faraday Mine Geological Context

• Location: Near Bancroft, Ontario, a region famous for its mineral diversity.
• Geology:
  • The Faraday Mine lies within the Grenville Province, a complex of metamorphic rocks rich in uranium deposits.
  • Primary uranium minerals (e.g., uraninite) occur in pegmatites and metamorphic rocks, which undergo oxidation to produce secondary minerals like uranophane and parauranophane.
• Associated Minerals:
  • Other uranium-bearing minerals: Uraninite, autunite, torbernite.
  • Silicate and phosphate minerals: Quartz, apatite, fluorite.

Mineralogical Significance

1. Scientific Importance:
   • Uranophane and parauranophane help geologists understand uranium mobility and the environmental conditions of uranium oxidation and deposition.
   • Their presence in secondary deposits aids in reconstructing the alteration history of primary uranium ores.
2. Collector’s Interest:
   • These minerals are highly prized for their bright coloration, crystal habits, and association with historic uranium mining operations like the Faraday Mine.

Approx. specimen size: 45mm x 40mm x 25mm

Approx. specimen activity on an SE International Ranger EXP: 3300 cpm