| Uranophane | |
| Category: | Uranyl neso- and polysilicates |
| Formula: | Ca(UO2)2[HSiO<sub>4</sub>]2·5H2O |
| Molweight: | 586.36 g/mol |
| Imasymbol: | Urp-α[1] |
| Strunz: | 9.AK.15 |
| System: | Monoclinic |
| Class: | Sphenoidal (2) (same H-M symbol) |
| Symmetry: | P21 |
| Unit Cell: | a = 15.85 Å, b = 6.98 Å c = 6.64 Å; β = 97.45°; Z = 2 |
| Color: | Light yellow, lemon-yellow, honey-yellow, straw-yellow, green-yellow |
| Habit: | Crystals occur as stellate needle aggregates; as fibrous crusts, and massive |
| Cleavage: | Perfect |
| Fracture: | Uneven |
| Tenacity: | Brittle |
| Mohs: | 2.5 |
| Luster: | Vitreous to pearly; waxy or dull when massive |
| Streak: | Yellowish white |
| Diaphaneity: | Translucent to subtranslucent |
| Gravity: | 3.81–3.90 |
| Opticalprop: | Biaxial (−) |
| Refractive: | nα = 1.643 nβ = 1.666 nγ = 1.669 |
| Birefringence: | δ = 0.026 |
| Pleochroism: | Weak; X = colorless; Y = pale canary-yellow; Z = canary-yellow |
| 2V: | 32° to 45°, measured |
| Fluorescence: | Weak yellow-green under both short and long UV |
| Other: | Radioactive |
| References: | [2] [3] [4] |
Uranophane (Ca(UO2)2(SiO3OH)2·5H2O), also known as uranotile, is a rare calcium uranium silicate hydrate mineral that forms from the oxidation of other uranium-bearing minerals. It has a yellow color and is radioactive.
Alice Mary Weeks, and Mary E. Thompson of the United States Geological Survey, identified uranophane in 1953.[5]
Classic samples have been produced at Madawaska Mine near Bancroft, Ontario.[6]