Ferroselite
| Ferroselite/Dzharkenite | |
|---|---|
Ferroselite found in Argentina | |
| General | |
| Category | Selenide mineral |
| Formula | FeSe2 |
| IMA symbol | Fse |
| Strunz classification | 2.EB.10a |
| Crystal system | Orthorhombic |
| Space group | Pnnm (no. 58) |
| Identification | |
| Color | Steel-gray to tin-white with a rose tint, brass yellow |
| Crystal habit | Acicular prismatic |
| Twinning | Stellate and cruciform twins common |
| Mohs scale hardness | 6 – 6.5 |
| Luster | Metallic |
| Streak | Black |
| Specific gravity | 7.20 |
| Refractive index | Opaque |
| Pleochroism | Distinct |
| Solubility | insoluble in water |
| References | |
Orthorhombic ferroselite and its isometric polymorph dzharkenite are iron selenides of general formula FeSe2 precipitated under reducing conditions in anoxic environments. They are a source of selenium in the Rocky Mountains where selenium occurrence is associated with Upper Cretaceous shale deposits.
In the frame of safety assessment calculations made for deep disposal of high-level radioactive waste, ferroselite and dzharkenite are also considered in geochemical calculations as one of the mineral phases limiting the solubility of Selenium-79.