Metazeunerite
| Metazeunerite | |
|---|---|
|
|
| General | |
| Category | Phosphate minerals |
|
Formula (repeating unit) |
Cu(UO2)2(AsO4)2·8H2O |
| Strunz classification | 8.EB.10 |
| Crystal system | Tetragonal |
| Crystal class | Dipyramidal (4/m) (same H-M symbol) |
| Space group | P4/n |
| Unit cell | a = 7.1094 Å, c = 17.416 Å; Z = 2 |
| Identification | |
| Color | Varies from pale to green |
| Crystal habit | Tabular rectangular crystals with two pinacoid faces; foliated or micaceous aggregates |
| Twinning | Merohedrally twinned |
| Cleavage | Perfect on {001}; distinct on {010} |
| Fracture | Uneven |
| Tenacity | Brittle |
| Mohs scale hardness | 2-2.5 |
| Luster | Vitreous to dull |
| Streak | Pale green |
| Diaphaneity | Transparent to translucent |
| Specific gravity | 3.87 |
| Optical properties | Uniaxial(-) |
| Refractive index | nw=1.643-1.651 nε=1.623-1.635 |
| Birefringence | .020 |
| Pleochroism | Weak |
| Other characteristics | Radioactive |
| References | |
Metazeunerite is an arsenate mineral with a chemical formula of Cu(UO2)2(AsO4)2·8H2O. The origin of this mineral comes from the dehydration process that metazeunerite must go through, and its association with zeunerite. As dehydration occurs, zeunerite loses an electron and is then metamorphosed into metazeunerite.
Its crystal system is tetragonal and its crystal class is 4/m, which is also called the tetragonal-dipyramidal class because it only has a vertical four-fold rotation axis that is perpendicular to the symmetry plane. When looking at a thin section, metzeunerite is anisotropic, meaning that it has pleochroism. When a mineral is anisotropic, one can see whether it is uniaxial or biaxial, depending on how fast the rays of light are moving through the mineral. This mineral is uniaxial negative due to the ordinary ray being slower than the extraordinary ray.
Metazeunerite is an uncommon radioactive secondary mineral found in "arsenic bearing hydrothermal uranium deposits" across the world. This widespread mineral occurs specifically in Europe, western North America, Australia, Brazil and Chile, Namibia, and Kazakhstan. It is currently studied through thermal decomposition by calculating the different levels of dehydration, as zeunerite is transformed into metazeunerite.
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