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.
| Uranophane |
|---|
 |
| General |
|---|
| Category | Uranyl neso- and polysilicates |
|---|
Formula
(repeating unit) | Ca(UO2)2[HSiO4]2·5H2O |
|---|
| Strunz classification | 9.AK.15 |
|---|
| Crystal system | Monoclinic |
|---|
| Crystal class | Sphenoidal (2)
(same H-M symbol) |
|---|
| Space group | P21 |
|---|
| Unit cell | a = 15.85 Å, b = 6.98 Å
c = 6.64 Å; β = 97.45°; Z = 2 |
|---|
| Identification |
|---|
| Formula mass | 586.36 g/mol |
|---|
| Color | Light yellow, lemon-yellow, honey-yellow, straw-yellow, green-yellow |
|---|
| Crystal habit | Crystals occur as stellate needle aggregates; as fibrous crusts, and massive |
|---|
| Cleavage | {100} Perfect |
|---|
| Fracture | Uneven |
|---|
| Tenacity | Brittle |
|---|
| Mohs scale hardness | 2.5 |
|---|
| Luster | Vitreous to pearly; waxy or dull when massive |
|---|
| Streak | Yellowish white |
|---|
| Diaphaneity | Translucent to subtranslucent |
|---|
| Specific gravity | 3.81 - 3.90 |
|---|
| Optical properties | Biaxial (-) |
|---|
| Refractive index | 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 angle | 32° to 45°, measured |
|---|
| Ultraviolet fluorescence | Weak yellow-green under both short and long UV |
|---|
| Other characteristics |  Radioactive |
|---|
| References |
|
|---|