| Schoepite | |
| Category: | Uranium minerals |
| Formula: | (UO2)8O2(OH)12 • 12(H2O) |
| Imasymbol: | Sho[1] |
| Strunz: | 4.GA.05 |
| System: | Orthorhombic |
| Class: | Pyramidal (mm2) H-M symbol: (mm2) |
| Symmetry: | P21ca |
| Unit Cell: | a = 14.33 Å, b = 16.79 Å c = 14.73 Å; Z = 4 |
| Color: | Amber, lemon- or sulfur yellow |
| Habit: | Commonly as tabular equant, to short prismatic crystals; rarely in microcrystalline aggregates |
| Cleavage: | [001] Perfect, [010] indistinct |
| Tenacity: | Brittle |
| Mohs: | 2.5 |
| Luster: | Adamantine |
| Streak: | Yellow |
| Diaphaneity: | Transparent to translucent |
| Gravity: | 4.8 |
| Opticalprop: | Biaxial (−) |
| Refractive: | nα = 1.690 nβ = 1.714 nγ = 1.735 |
| Birefringence: | δ = 0.045 |
| Pleochroism: | X = almost colorless; Y = Z = lemon-yellow to golden yellow |
| 2V: | Measured: 89° |
| Fluorescence: | Short and long UV = pale green |
| Other: | Radioactive |
| References: | [2] |
Schoepite, empirical formula (UO2)8O2(OH)12·12(H2O)[3] is a rare alteration product of uraninite in hydrothermal uranium deposits. It may also form directly from ianthinite. The mineral presents as a transparent to translucent yellow, lemon yellow, brownish yellow, or amber orthorhombic tabular crystals. Although over 20 other crystal forms have been noted; rarely in microcrystalline aggregates. When exposed to air schoepite converts over a short time to the metaschoepite form (UO3·H2O,) within a few months of being exposed to ambient air.[4]
The hardness is 2.5, density is 4.8 g/cm3, and it streaks yellow.
It was first described from specimens from Shinkolobwe mine in Belgian Congo in 1923,[3] several additional localities are known.
Schoepite was named to honor Alfred Schoep (1881–1966), Professor of Mineralogy at the University of Ghent, Belgium.[5]