Images
Formula: Ba(U6+O2)2(V5+O4)2.5H2O
Hydrated vanadate,
francevillite group,
uranyl mineral, forms a series with
curienite
Crystal System: Orthorhombic
Specific gravity: 4.55 measured, 4.56 calculated
Hardness: 3
Streak: Light yellow
Colour: Lemon-yellow, yellow-orange, orange, greenish yellow, green, brown
Luminescence: Does not fluoresce under UV
Solubility:
Common impurities:
Very strongly RADIOACTIVE
Environments
Localities
At the type locality, the Mounana Mine, Mounana, Léboumbi-Leyou Department, Haut-Ogooué Province, Gabon,
francevilleite occurs as impregnations, cryptocrystalline veinlets and crystal-plates several millimeters in
thickness in sandstone. Associated Minerals include
vanuralite, uranopilite,
torbernite, mottramite,
kasolite, johannite,
duttonite, dewindtite,
curienite, chervetite and
carnotite
(Mindat).
Francevillite from the Mounana Mine - Image
Back to Minerals