Tyuyamunite
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| Tyuyamunite | |
|---|---|
 | |
| General | |
| Category | Vanadate mineral |
| Formula | Ca(UO2)2V2O8·(5–8)H2O |
| IMA symbol | Tyu[1] |
| Strunz classification | 4.HB.25 |
| Dana classification | 40.2a.26.1 |
| Crystal system | Orthorhombic |
| Crystal class | Dipyramidal (mmm) H-M symbol: (2/m 2/m 2/m) |
| Space group | Pnna |
| Unit cell | a = 10.63 Å, b = 28.36 Å c = 20.4 Å; Z = 4 |
| Identification | |
| Colour | Canary yellow, lemon-yellow; greenish yellow (upon exposure to sunlight) |
| Crystal habit | Platy crystals often in radiating sprays, coatings, massive |
| Cleavage | Perfect on {001}, micaceous; distinct on {100} & {010} |
| Mohs scale hardness | 1+1⁄2 – 2 |
| Lustre | Adamantine, waxy, pearly on {101}, dull |
| Streak | Yellow |
| Diaphaneity | Translucent to opaque |
| Specific gravity | 3.57 – 4.35 |
| Optical properties | Biaxial (−) |
| Refractive index | nα = 1.675 nβ = 1.860 – 1.870 nγ = 1.885 – 1.895 |
| Birefringence | 0.210 – 0.220 |
| Pleochroism | weak: X = nearly colourless, Y = pale canary yellow, Z = canary yellow |
| 2V angle | 30° to 45° |
| Dispersion | none |
| Other characteristics |  Radioactive |
| References | [2][3][4][5] |
Tyuyamunite (pronounced tuh-YOO-ya-moon-ite) is a very rare uranium mineral with formula Ca(UO2)2V2O8·(5–8)H2O. It is a member of the carnotite group. It is a bright, canary-yellow color because of its high uranium content. Also, because of tyuyamunite's high uranium content, it is radioactive.[6] It was named by Konstantin Avtonomovich Nenadkevich, in 1912, after its type locality, Tyuya-Muyun, Fergana Valley, Kyrgyzstan.[3]
