Francevillite with Curienite Locality : Mounana Mine, Franceville , Haut-Ogooué, Gabon - Toptype deposit Size : 23 x 17 cm Size of crystal 0.8cm — Photo: Didier Descouens · CC BY-SA 3.0
Francevillite
A strongly radioactive orange-yellow barium-lead uranyl vanadate of the tyuyamunite series.
Intro adapted from Wikipedia (CC BY-SA).
Francevillite is an IMA-recognized mineral species in the vanadate class, with the chemical formula Ba(UO₂)₂(VO₄)₂·5H₂O.
It crystallizes in the orthorhombic crystal system (space group Pcan). It is a member of the Fritzscheite structural group.
Key properties: Mohs hardness 3; specific gravity 4.55; refractive index 1.893; optically biaxial.
IMA symbol Fvl, IMA status: approved, named in 1957.
Found in the oxidized zone of a Pb-bearing U–V deposit (Mounana mine, Gabon).
It is found associated with Curienite, duttonite, vanuralite, chervetite, mottramite, carnotite, dewindtite, torbernite, uranopilite, johannite, kasolite (Mounana mine, Gabon).
The name refers to its original occurrence near Franceville, Gabon.