{{infobox mineral |boxbgcolor=#dacc1c| name = Francevillite | category = Vanadate mineral | image = Francevillite-Mounanaite-Curienite-20877.jpg | imagesize = 260px | alt = | caption = Yellow crystals of francevillite on matrix with small mounanaite crystals (specimen size, 4 x 3.5 x 1 cm) | formula = {{chem2|(Ba,Pb)(UO2)2V2O8*5(H2O)}} | IMAsymbol = Fvl<ref>{{Cite journal|last=Warr|first=L.N.|date=2021|title=IMA–CNMNC approved mineral symbols|journal=Mineralogical Magazine|volume=85|issue=3|pages=291–320|doi=10.1180/mgm.2021.43|bibcode=2021MinM...85..291W|s2cid=235729616|doi-access=free}}</ref> | molweight = | strunz = 4.HB.15 | dana = 40.02a.27.01 | system = Orthorhombic | class = Dipyramidal (mmm) <br/>H-M symbol: (2/m 2/m 2/m) | symmetry = ''Pcan'' | unit cell = a = 10.41, b = 8.51 <br/>c = 16.76 [Å]; Z = 4 | color = Lemon-yellow, yellow-orange, orange, greenish yellow; green, brown | colour = | habit = Aggregates and incrustations of crystals, also massive, in veinlets and as impregnations | twinning = | cleavage = On {001}, perfect | fracture = | tenacity = | mohs = 3 | luster = Adamantine - pearly | streak = Light yellow | diaphaneity = Semitransparent | gravity = 4.55 | density = | polish = | opticalprop = Biaxial (-) | refractive = n<sub>α</sub> = 1.750 - 1.785 n<sub>β</sub> = 1.910 - 1.952 n<sub>γ</sub> = 1.945 - 2.002 | birefringence = δ = 0.195 - 0.217 | pleochroism = X = colorless; Y = Z = yellow | 2V = Measured: 52°, Calculated: 46° to 52° | dispersion = | extinction = | length fast/slow = | fluorescence= | absorption = | melt = | fusibility = | diagnostic = | solubility = | other = 25px Radioactive | alteration = | references = <ref name=Handbook>[http://rruff.geo.arizona.edu/doclib/hom/francevillite.pdf Handbook of Mineralogy]</ref><ref name=Mindat>[http://www.mindat.org/min-1589.html Mindat.org]</ref><ref name=Webmin>[http://www.webmineral.com/data/Francevillite.shtml Webmineral data]</ref><ref>[http://www.uraniumminerals.com/UTh/Francevillite.htm Francevillite] {{Webarchive|url=https://web.archive.org/web/20091102170041/http://www.uraniumminerals.com/UTh/Francevillite.htm |date=2009-11-02 }} at [http://www.uraniumminerals.com/ Uranium and Thorium Minerals of the World]</ref> }}
'''Francevillite''' is a uranyl-group vanadate mineral in the tyuyamunite series. Its chemical formula is {{chem2|(Ba,Pb)(UO2)2V2O8*5(H2O)}}. Francevillite is a strongly radioactive mineral. It is typically orange, yellow or brownish yellow. It forms a series with curienite.<ref name=Handbook/>
==Occurrence==
Francevillite occurs in the oxidized zone of lead-bearing uranium–vanadium deposits.<ref name=Handbook/> Francevillite was first described in 1957 for an occurrence in its type locality of the idle Mounana uranium mine, near Franceville, Haut-Ogooué, Gabon and was named for the city.<ref name=Mindat/><ref name=Webmin/>
At its type locality it is associated with curienite (a closely related uranyl vanadate), chervetite (a lead vanadate), and mounanaite (another lead vanadate). At other localities, francevillite is associated with duttonite, vanuralite, mottramite, carnotite, dewindtite, torbernite, uranopilite, johannite and kasolite.<ref name=Handbook/>
<gallery widths="250px" heights="200px" perrow="1"> File:Francevillite.jpg|Yellow curienite on bright orange francevillite, in a specimen from their mutual type locality, the Mounana uranium mine, near Franceville. Specimen size: 23x17cm. File:Francevillite-Chervetite-Curienite-64420.jpg|Francevillite (orange) with Curienite (yellow) and Chervetite, Mounana Mine, Franceville, Haut-Ogooué Province, Gabon. Overall size 8.7 x 6.1 x 2.1 cm. </gallery>
==References== {{Reflist}}
{{Commons category|Francevillite}}
Category:Uranium(VI) minerals Category:Vanadate minerals Category:Orthorhombic minerals Category:Minerals in space group 60