Sharp orange crystal of the extremely rare Fe-Ce molybdate mineral tancaite-(Ce) from the TL and only known locality worldwide (Punta de Su Seinargiu, Sarroch, Cagliari Province, Sardinia, Italy) in a white contrasting matrix. Ex. Erich Laskowski collection (USA). — Photo: David Hospital · CC BY 4.0
Tancaite-(Ce)
Tancaite-(Ce) is a very rare molybdate mineral with the formula FeCe(MoO4)3•3H2O. It was found in Punta de Su Seinargiu locality on Sardinia, Italy. Red crystals of tancaite-(Ce) resemble modified cubes, but the mineral is trigonal (space group R-3). The type locality of tancaite-(Ce) is also a place of discovery of other molybdate minerals, including thorium molybdates ichnusaite and nuragheite.
Intro adapted from Wikipedia (CC BY-SA).
Tancaite-(Ce) is an IMA-recognized mineral species in the molybdate class, with the chemical formula FeCe(MoO₄)₃·3H₂O.
It crystallizes in the hexagonal crystal system (space group R-3).
Key properties: Mohs hardness 4–4.5; specific gravity 3.738; Yellow streak; Vitreous to adamantine luster.
IMA symbol Tca-Ce, IMA status: approved, named in 2009.
A secondary mineral formed in the oxidation zone of a sulfide ore vein in granite.
It is found associated with Quartz, muscovite, molybdenite, pyrite, mendozavilite.
The mineral was named to honor Giuseppe Tanca (b. 1943), an Italian amateur mineralogist, who discovered the mineral. A suffix indicates the dominant rare-earth element.