Jarosite
Jarosite is a basic hydrous sulfate of potassium and ferric iron (Fe-III) with a chemical formula of KFe3(SO4)2(OH)6. This sulfate mineral is formed in ore deposits by the oxidation of iron sulfides. Jarosite is often produced as a byproduct during the purification and refining of zinc and is also commonly associated with acid mine drainage and acid sulfate soil environments.
| Jarosite | |
|---|---|
Jarosite on quartz from the Arabia District, Pershing County, Nevada | |
| General | |
| Category | Sulfate minerals |
| Formula (repeating unit) | KFe3(SO4)2(OH)6 |
| IMA symbol | Jrs |
| Strunz classification | 7.BC.10 |
| Dana classification | 30.2.5.1 |
| Crystal system | Trigonal |
| Crystal class | Rhombohedral (3m) H-M symbol: (3m) |
| Space group | R3m |
| Unit cell | a = 7.304 Å, c = 17.268 Å; Z = 3 |
| Identification | |
| Formula mass | 500.8 g/mol |
| Color | Amber yellow or dark brown |
| Crystal habit | Crystals are usually pseudocubic or tabular, also as granular crusts, nodules, fibrous masses or concretionary. |
| Cleavage | Distinct on {0001} |
| Fracture | Uneven to conchoidal |
| Tenacity | Brittle |
| Mohs scale hardness | 2.5–3.5 |
| Luster | Subadamantine to vitreous, resinous on fractures |
| Streak | light yellow |
| Diaphaneity | Transparent to translucent |
| Specific gravity | 2.9 to 3.3 |
| Optical properties | Uniaxial (−), usually anomalously biaxial with very small 2V |
| Refractive index | nω = 1.815 to 1.820; nε = 1.713 to 1.715 |
| Birefringence | 0.102 to 0.105 |
| Pleochroism | E colorless, very pale yellow, or pale greenish yellow, O deep golden yellow or reddish brown |
| Solubility | Insoluble in water. Soluble in HCl. |
| Other characteristics | Strongly pyroelectric. Non-fluorescent. Barely detectable radioactivity |
| References | |
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.