Bílinite (Fe2+Fe23+(SO4)·22H2O) is an iron sulfate mineral. It is a product of the oxidation 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 , Czech Republic was named 'bílinite' (Palache , et al., 1969). This mineral possibly occurs on Mars.