Bermanite - Encyclopedia
Class : Phosphates, arsenates, vanadates
Subclass : Hydrated phosphates
Crystal System : Monoclinic
Chemistry : Mn3(PO4)2(OH)2 4H2O
Rarity : Fairly common
Beraunite is a hydrated iron phosphate of secondary origin which is formed by alteration of primary phosphates, in particular triphylite and lithiophyllite, in granitic pegmatites. Its name was given to it in honor of Harry Berman, professor of mineralogy at Harvard University. It occurs in tabular crystals, often twinned, 5 mm at most, usually grouped in sheaves or rosettes ; also in coatings and lamellar masses. It is a red to dark reddish-brown mineral, darkening on exposure.
Main photo : Bermanite from Jocão claim, Minas Gerais, Brazil © Gianfranco Ciccolini
Bermanite in the World
Twinning and special crystallizations
Many twins are known : commonly polysynthetic around [101] with {101} as composition plane or around [101] with {101} as composition plane. On {001} around [100], or with 2 or more individuals on {301} around [100] producing composite twins.
Fakes and treatments
No fake or treatment identified for this mineral species.
Hardness : 3.5
Density : 2.85
Fracture : Irregular
Trace : Red to brown
TP : Translucent to transparent
RI : 1.685 to 1.751
Birefringence : 0.063
Optical character : Biaxial -
Pleochroism : Visible
Fluorescence : None
Solubility : Nitric acid
Magnetism : None
Radioactivity : None