Bílinite (Fe2+Fe23+(SO4)·22H2O) is an iron sulfate mineral. It is a product of the oxidation of pyrite in water. It is an acidic mineral that has a pH of less than 3 and is harmful to the environment when it comes from acid rock drainage (Keith et al., 2001).
| Bílinite | |
|---|---|
 | |
| General | |
| Category | Sulfate mineral |
| Formula (repeating unit) | Fe2+Fe3+2(SO4)·22H2O |
| IMA symbol | Bli[1] |
| Strunz classification | 7.CB.85 |
| Dana classification | 29.07.03.05 |
| Crystal system | Monoclinic |
| Crystal class | Prismatic (2/m) (same H-M symbol) |
| Space group | P21/c |
| Identification | |
| Color | White to yellowish |
| Crystal habit | Fibrous in radial aggregates |
| Mohs scale hardness | 2 |
| Luster | Vitreous - silky |
| Streak | White |
| Diaphaneity | Semitransparent |
| Specific gravity | 1.87 |
| Optical properties | Biaxial (+/-) |
| Refractive index | nα = 1.480 - 1.482 nβ = 1.500 nγ = 1.489 - 1.493 |
| Birefringence | δ = 0.009 - 0.011 |
| Solubility | Soluble in water |
| References | [2][3][4] |
Bílinite was first discovered near Bílina, Czech Republic which is why the mineral was named 'bílinite' (Palache, et al., 1969). This mineral possibly occurs on Mars.
Composition
The weight percent oxide is as follows:[2]
| Oxide | Composition |
|---|---|
| SO3 | 33.78 |
| Fe2O3 | 16.84 |
| FeO | 7.58 |
| H2O | 41.8 |
| Total | 100 |
Related minerals
Related minerals to bílinite include jarosite, which is an iron sulfate salt, lepidocrocite, schwertmannite, ferricopiapite, and copiapite (Marion, et al., 2008).
Special characteristics
Boulder Creek is a stream at Iron Mountain in Shasta County, California. The stream drains into the Sacramento River and San Francisco Bay. The water in this stream is contaminated from the mixture of the groundwater and surface streams due to mining. The pH is low and acidic due to the oxidation of pyrite in water. This results in the formation of sulfuric acid and bílinite (Keith, et al., 2001).
References
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