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Francevillite

Field	Value
boxbgcolor	#dacc1c	name = Francevillite
category	Vanadate mineral
image	Francevillite-Mounanaite-Curienite-20877.jpg
imagesize	260px
caption	Yellow crystals of francevillite on matrix with small mounanaite crystals (specimen size, 4 x 3.5 x 1 cm)
formula
IMAsymbol	Fvl
strunz	4.HB.15
dana	40.02a.27.01
system	Orthorhombic
class	Dipyramidal (mmm)
H-M symbol: (2/m 2/m 2/m)
symmetry	Pcan
unit cell	a = 10.41, b = 8.51
c = 16.76 [Å]; Z = 4
color	Lemon-yellow, yellow-orange, orange, greenish yellow; green, brown
habit	Aggregates and incrustations of crystals, also massive, in veinlets and as impregnations
cleavage	On {001}, perfect
mohs	3
luster	Adamantine - pearly
streak	Light yellow
diaphaneity	Semitransparent
gravity	4.55
opticalprop	Biaxial (-)
refractive	nα = 1.750 - 1.785 nβ = 1.910 - 1.952 nγ = 1.945 - 2.002
birefringence	δ = 0.195 - 0.217
pleochroism	X = colorless; Y = Z = yellow
2V	Measured: 52°, Calculated: 46° to 52°
other	[[Image:Radioactive.svg	25px]] Radioactive
references

H-M symbol: (2/m 2/m 2/m) c = 16.76 [Å]; Z = 4 | length fast/slow =

Francevillite is a uranyl-group vanadate mineral in the tyuyamunite series. Its chemical formula is . Francevillite is a strongly radioactive mineral. It is typically orange, yellow or brownish yellow. It forms a series with curienite.

Occurrence

Francevillite occurs in the oxidized zone of lead-bearing uranium–vanadium deposits. 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.

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.

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.

References

Warr, L.N.. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine.
[http://rruff.geo.arizona.edu/doclib/hom/francevillite.pdf Handbook of Mineralogy]
[http://www.mindat.org/min-1589.html Mindat.org]
[http://www.webmineral.com/data/Francevillite.shtml Webmineral data]
[http://www.uraniumminerals.com/UTh/Francevillite.htm Francevillite] {{Webarchive. link. (2009-11-02 at [http://www.uraniumminerals.com/ Uranium and Thorium Minerals of the World])

Info: Wikipedia Source

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uranium(vi)-minerals vanadate-minerals orthorhombic-minerals minerals-in-space-group-60

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