Bílinite

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
CategorySulfate mineral
Formula
(repeating unit)
Fe2+Fe3+2(SO4)·22H2O
Strunz classification7.CB.85
Dana classification29.07.03.05
Crystal systemMonoclinic
Crystal classPrismatic (2/m)
(same H-M symbol)
Space groupP21/c
Identification
ColorWhite to yellowish
Crystal habitFibrous in radial aggregates
Mohs scale hardness2
LusterVitreous - silky
StreakWhite
DiaphaneitySemitransparent
Specific gravity1.87
Optical propertiesBiaxial (+/-)
Refractive indexnα = 1.480 - 1.482 nβ = 1.500 nγ = 1.489 - 1.493
Birefringenceδ = 0.009 - 0.011
SolubilitySoluble in water
References[1][2][3]

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:[1]

OxideComposition
SO333.78
Fe2O316.84
FeO7.58
H2O41.8
Total100

Related minerals to bílinite include jarosite, which is an iron sulfate salt, lepidocrocite, schwetmannite, 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

  • Keith, David C., Runnells, Donald D., Esposito, Kenneth J., Chermak, John A., Levy, David B., Haaula, Steven R., Watts, Malcolm, Hall, Larry. (2001) Geochemical models of the impact of acidic groundwater and evaporative sulfate salts on Boulder Creek at Iron Mountain, California. Applied Geochemistry 16, 947-961.
  • Marion, Giles M., Kargel, Jeffrey S., Catling, David C. (2008) Modeling ferrous-ferric iron chemistry with application to Martian surface geochemistry. Geochimica Et cosmochimica Acta 72, 242-266.
  • Tosca, Nicholas J, McLennan Scott, M, (2009) Experimental constraints on the evaporation of partially oxidized acid-sulfate waters at the martian surface. Geochimica Et Cosmochmica Acta 73, 1205–1222.
  • Palache, C. H,. Berman, and C. Frondel, Bol'shakov, A.P. And L.I. Ptushko (1951) Fe2+ Fe23+ (SO4)4 *22(H2O). Handbook of Mineralogy. Mineral Data Publishing (Republish by the Mineralogical Society of America).
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