Geographic Minerals



Bílinite, formula- [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 was first discovered near Bílina, the Czech Republic which is why the mineral was named ‘bílinite’ (Palache, et al., 1969). This mineral possibly occurs on Mars.

General Information

  • Category: Sulfate mineral
  • Formula: [Fe2+ Fe23+(SO4)·22H2O]
  • Crystal system: Monoclinic
  • Crystal class: Prismatic (2/m) (same H-M symbol)
  • Member of: Halotrichite Group.


  • 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

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 with 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.


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