Grandidierite - Encyclopedia
Class : Silicates
Subclass : Nesosilicates
Crystal system : Orthorhombic
Chemistry : (Mg, Fe)Al3(BO3)(SiO4)O2
Rarity : Rare
Grandidierite is a rare mineral, accessory to aplites and pegmatites rich in boron, and in certain rocks of regional metamorphism. It owes its name to the French geographer and naturalist Alfred Grandidier, who discovered it in Madagascar. It occurs in cleavable masses or in grains, sometimes in elongated orthorhombic prisms exceptionally terminate in a pyramid, and more rarely in tabular crystals. Translucent to transparent, grandidierite is dark bluish green to deep blue. It is a mineral occasionally cut into gemstone.
Grandidierite in the World
Grandidierite in France
This mineral is not present in the French underground.
Twinning
No twin known for this mineral species.
Fakes and scams
No scam known for this mineral.
Hardness : 7.5
Density : 2.98 to 2.99
Fracture : Conchoidal
Trace : White
TP : Translucent to transparent
RI : 1.590 to 1.639
Birefringence : 0.033 to 0.037
Optical character : Biaxial -
Pleochroism : Visible
Fluorescence : None
Solubility : Insoluble
Magnetism : None
Radioactivity : None