Ulfanderssonite-(Ce)
Ulfanderssonite-(Ce) is an IMA-recognized mineral species in the silicate class, with the chemical formula (Ce₁₅Ca)Σ₁₆Mg₂(SiO₄)₁₀(SiO₃OH)(OH,F)₅Cl₃.
It crystallizes in the monoclinic crystal system (space group Cm).
Key properties: Mohs hardness 5–6; specific gravity 4.972; White streak; Vitreous to greasy luster; optically biaxial.
IMA symbol Ulf-Ce, IMA status: approved, named in 2017.
Found as a primary mineral in metasomatic Fe-REE skarn mineralization of the Bastnäs-type.
It is found associated with Västmanlandite-(Ce), bastnäsite-(Ce), phlogopite, talc, magnetite.
The mineral was named to honor Ulf B. Andersson (b. 1960), a Swedish geologist-petrologist for his contributions to the understanding of the genesis of REE deposits of the Bastnäs type.