Fourmarierite - Encyclopedia
FORSTERITE
Class : Oxides and hydroxides
Subclass : Uranyl hydroxides
Crystal system : Orthorhombic
Chemistry : Pb(UO2)4O3(OH)4 4H2O
Rarity : Rare
Fourmarierite is one of seven currently known mixed oxides of uranium and lead. When they are dominant, these minerals mark the oxidized layers which coat the residual pitchblende with their orange to red color, hence their generic name "orange gummite". It was named in honor of the Belgian geologist Paul Fourmarier, professor at the University of Liège. Fourmarierite is carmine red to orange-red in color, rarely orange, and forms small elongated tabular crystals with pseudohexagonal outlines, sometimes acicular crystals. It also exists in small compact cryptocrystalline masses. It associates with other uranium oxides (kasolite, billietite, curite, becquerelite, etc...) in zones of pitchblende alteration.
Main photo : Fourmarierite from Shinkolobwe Mine, Kambove, Haut-Katanga, D. R. of Congo © Jason B. Smith
FORSTERITE
Fourmarierite in the World
FORSTERITE
Twinning
No twin known for this mineral species.
Fakes and treatments
No fakes recorded for this mineral species.
FORSTERITE
Hardness : 3 to 4
Density : 6.05
Fracture : Undetermined
Streak : Undetermined
TP : Translucent to transparent
RI : 1.850 to 1.970
Birefringence : 0.040 to 0.105
Optical character : Biaxial -
Pleochroism : Visible
Fluorescence : None
Solubility : Acids
Magnetism : None
Radioactivity : Very strong