Curite
| Curite | |
|---|---|
| General | |
| Category | Oxide mineral |
| Formula | Pb3[(UO2)4|O4|(OH)3]2·2 H2O |
| IMA symbol | Cui |
| Strunz classification | 4.GB.55 |
| Crystal system | Orthorhombic |
| Crystal class | orthorhombic-dipyramidal; 2/m 2/m 2/m |
| Space group | Pnam |
| Unit cell | a = 12.551 Å, b = 13.02 Å, c = 8.40 Å; Z = 2 |
| Identification | |
| Color | red, reddish orange, brownish yellow. |
| Crystal habit | needles, acicular, massive, compact earthy. |
| Cleavage | {100}, imperfect} |
| Fracture | uneven |
| Tenacity | brittle |
| Mohs scale hardness | 4-5 |
| Luster | adamantine |
| Streak | orange |
| Diaphaneity | transparent |
| Density | measured: 6.98–7.4; calculated: 7,37 |
| Optical properties | biaxial (-) |
| Refractive index | nα = 2.060 nβ = 2.110 nγ = 2.150 |
| Birefringence | 0.090 |
| Pleochroism | Visible: X = b = pale yellow, Y = a = light red-orange, Z = c = dark red-orange |
| 2V angle | 70° (measured); 80° (calculated) |
| Other characteristics | Radioactive |
Curite is a rare mineral with the chemical composition Pb3[(UO2)4|O4|(OH)3]2·2 H2O. It is therefore a hydrated lead uranyl oxide, which forms red needles or orange, massive aggregates.