Beraunite - Encyclopedia
Class : Phosphates, arsenates, vanadates
Subclass : Hydrated phosphates
Crystal System : Monoclinic
Chemistry : Fe6(PO4)4(OH)5 6H2O
Rarity : Uncommon
Beraunite is an hydrated iron phosphate of secondary origin that forms by weathering of primary phosphates, including triphylite and lithiophyllite, in granitic pegmatites and some iron deposits. It owes its name to its place of discovery : the Hrbek mine, near Beraun (Czech Republic). It occurs in slightly elongated tabular crystals of 1 cm at most, often united in fibroradiated or spherulitic aggregates, or in discoid concretions. It is a dark greenish to dark greenish brown mineral when fresh, then dulls and opacifies in light to dark reddish to reddish brown hues.
Main photo : Beraunite from Indian Mountain, Alabama, USA © Henry Barwood
Beraunite in the World
Twinning and special crystallizations
Twins are known on {100}.
Fakes and treatments
No fake or treatment identified for this mineral species.
Hardness : 3 to 4
Density : 2.8 to 3
Fracture : Irregular
Trace : Green to yellow
TP : Translucent
RI : 1.707 to 1.820
Birefringence : 0.031
Optical character : Biaxial +
Pleochroism : Visible
Fluorescence : None
Solubility : Hydrochloric acid
Magnetism : None
Radioactivity : None