Fluocerite

Fluocerite, also known as tysonite, is a mineral consisting of cerium and lanthanum fluorides, with the chemical formula. The end members are classified as two different mineral types depending on the cation, fluocerite- and fluocerite-, corresponding respectively to lanthanum trifluoride and cerium trifluoride. Both crystallize in the trigonal system.
Fluocerite- was first described in 1845 from hydrothermal veins in granite in Sweden. Fluocerite- was first described in 1969 from the type [locality (geology)|type locality] in central Kazakhstan. The name tysonite was given in 1880 to the same type of mineral found in Colorado. Tysonite-type structure is used for rare-earth fluorides with the P3c1 space group structure.