Uranophane - Smith Hill Mine #2 Mine, Alstead, N.H., USA

Ca(UO₂)₂(SiO₃OH)₂ · 5H₂O

Uranophane - Smith Hill Mine #2, Alstead, N.H., USA

Uranophane is a rare, secondary uranium mineral typically found in oxidized uranium deposits. It is recognized for its striking yellow to greenish-yellow color and its fibrous to acicular crystal habit. Here are key details about Uranophane from the Smith Hill Mine #2 in Alstead, New Hampshire, USA:

Geological Context

• Location: The Smith Hill Mine #2, situated in Alstead, Cheshire County, New Hampshire, is known for its small-scale uranium and rare earth element deposits.
• Formation: Uranophane forms as a secondary mineral from the alteration of primary uranium-bearing minerals such as uraninite, often in the presence of silica and calcium.

Physical and Optical Properties

• Chemical Formula: $Ca(U{O}_2{)}_2(Si{O}_{3}OH{)}_2\cdot 5H_{2}O$
• Color: Bright yellow to greenish-yellow.
• Habit: Typically forms fibrous, acicular, or needle-like aggregates.
• Luster: Silky to vitreous.
• Transparency: Translucent to transparent.
• Hardness: ~2–3 on the Mohs scale.
• Specific Gravity: Approximately 3.81.

Significance and Collection

• Rarity: Uranophane is a rare collector's mineral, prized for its vibrant coloration and unique fibrous formations.
• Safety Note: As a uranium-bearing mineral, it is radioactive. Proper handling and storage are essential to minimize exposure to radiation.
• Local Significance: Specimens from Smith Hill Mine #2 are notable for their well-defined crystal habits and are sought after by mineral collectors familiar with New England’s mineralogical heritage.

Associated Minerals

• Uranophane often occurs with:
  • Uraninite
  • Autunite
  • Torbernite
  • Quartz
  • Other secondary uranium minerals

Historical Context

The Smith Hill Mine #2 is a lesser-known site in the United States' uranium mining history. While not a significant producer on a commercial scale, it has been a point of interest for geologists and mineral collectors due to its unique mineralogical finds.

Field Collection

• Accessibility: Access to the mine site may be restricted; permission may be required to collect specimens.
• Condition of Specimens: Specimens often exhibit weathering but retain their characteristic fibrous and brightly colored features.

Approx. specimen size: 50mm x 35mm x 15mm

Approx. specimen activity on an SE International Ranger EXP: 9700 cpm