NOVACEKITE

    Class : Phosphates, arsenates, vanadates
    Subclass : Uranyl arsenates
    Crystal system : Monoclinic
    Chemistry : Mg(UO2)2(AsO4)2 12H2O
    Rarity : Rare

Novacekite is an arsenate of uranium and magnesium which is found in the surface oxidation zone of some uranium deposits. It forms a series with its phosphorous equivalent : saltite. It owes its name to the Czech mineralogist Radim Novacek. Novacekite occurs in thick tablets united in subparallel aggregates, often intergrowing with zeunerite. Its color is lemon yellow to yellow-orange and yellow-green.

Main photo : 5 cm Novacekite from Pedra Preta pit, Serra das Éguas, Brumado, Bahia, Brazil © Rock Currier

Novacekite from Cuervo Mine, Chihuahua, Mexico © Peter Megaw
Novacekite from Bricco Volti - Monte Ortieul, Piedmont, Italy © Beppe Finello
Novacekite from the Clara Mine, Germany © Michael Förch
Novacekite from Rabejac, Hérault, France © Guy Bernadi

Novacekite in the World

Magnificent tabular crystals grouped in subaprallel or lamellar aggregates of 5 cm were discovered in the magnesite deposit of Pedra Preta, near Brumado (Bahia, Brazil), associated with zeunerite : these are the best known specimens. Novacekite is also present in the uranium veins of the Black Forest (Germany), in the Mexican veins of Aquilès Serdan and Chihuahua, as well as in the St-Just veins in English Cornwall.

Novacekite in France

In France, novacekite is known in small crystals in uranium deposits in the Lodève region such as Rabejac (Hérault), it has also been reported at Mont Oreb (Haute-Savoie).

Twinning

No twins known for this mineral species.

Fakes and treatments

No fakes recorded for this mineral species.


Hardness : 2 to 2.5
Density : 3.25 to 3.7
Fracture : Micaceous
Streak : Pale yellow

TP : Translucent to transparent
RI : 1.543 to 1.578
Birefringence : 0.032
Optical character : Biaxial -
Pleochroism : Visible
Fluorescence : Green to yellow

Solubility : -

Magnetism : NoneRadioactivity : Strong