Calcurmolite - Encyclopedia
Class : Sulfates, chromates, molybdates
Subclass : Uranyl molybdates
Crystal system : Monoclinic
Chemistry : Ca(UO2)3(MoO4)3(OH)2 11H2O
Rarity : Very rare
Calcurmolite is an extremely rare uranium and calcium molybdate from the oxidation zone of uranium deposits. It is formed by alteration of uraninite which it can pseudomorph, and concretizes the attraction of molybdenum and uranium for the organic matter present in sedimentary deposits. Note that, unlike vanadium, molybdenum only forms very rare supergene minerals with uranium ; only nine species are known to date. It owes its name to its chemical composition (calcium + uranium + molybdenum). Calcurmolite forms coatings, prismatic crystals, lamellar or rarely spherolitic aggregates, lemon yellow in color.
Main photo : Calcurmolite from Rabejac, Hérault, France © Leon Hupperichs
Calcurmolite in the World
Twinning
No twin known for this mineral species.
Fakes and treatments
No fake identified for this mineral species.
Hardness : 2 to 3
Density : -
Fracture : Irregular
Streak : Yellow
TP : Translucent
RI : 1.770 to 1.863
Birefringence : 0,088
Optical character : Biaxial -
Pleochroism : Visible
Fluorescence : Yellow-green
Solubility : -
Magnetism : None
Radioactivity : Strong