Gaudefroyite - Encyclopedia
Class : Carbonates, nitrates, borates
Subclass : Borates
Crystal system : Hexagonal
Chemistry : Ca4Mn3(BO3)3(CO3)(O,OH)3
Rarity : Very rare
Gaudrefroyite is a complex borate of calcium and manganese, whose structure includes CO3 groups. It is a very rare mineral present in some manganese deposits, particularly in limestone environments. It was named in honor of Abbe Christophe Gaudefroy, a French mineralogist who was particularly interested in the minerals of Morocco. Gaudefroyite occurs in acicular crystals or stubby prisms of purplish-blackish brown to black color. It is an occasional manganese ore.
Main photo : 1.8 cm gaudefroyite from N'Chwaning II Mine, South Africa © Jordi Fabre
Gaudefroyite in the World
Twinning
No twin known for this mineral species.
Fakes and treatments
No fakes recorded for this mineral species.
Hardness : 6
Density : 3.35 to 3.50
Fracture : Conchoidal
Streak : Brown
TP : Opaque
RI : 1.805 to 2.020
Birefringence : 0.210
Optical character : Uniaxial +
Pleochroism : Strong
Fluorescence : None
Solubility : -
Magnetism : None
Radioactivity : None