Fluocerite, also known as tysonite, is a mineral consisting of

cerium Cerium is a chemical element; it has Chemical symbol, symbol Ce and atomic number 58. It is a hardness, soft, ductile, and silvery-white metal that tarnishes when exposed to air. Cerium is the second element in the lanthanide series, and while it ...

and

lanthanum Lanthanum is a chemical element; it has symbol La and atomic number 57. It is a soft, ductile, silvery-white metal that tarnishes slowly when exposed to air. It is the eponym of the lanthanide series, a group of 15 similar elements bet ...

fluoride Fluoride (). According to this source, is a possible pronunciation in British English. is an Inorganic chemistry, inorganic, Monatomic ion, monatomic Ion#Anions and cations, anion of fluorine, with the chemical formula (also written ), whose ...

s, with the chemical formula . The end members are classified as two different mineral types depending on the

cation An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convent ...

, fluocerite-(Ce) and fluocerite-(La), corresponding respectively to

lanthanum trifluoride Lanthanum trifluoride is a refractory ionic compound of lanthanum and fluorine. The chemical formula is . The LaF3 structure Bonding is ionic with lanthanum highly coordinated. The cation sits at the center of a trigonal prism. Nine fluorine ...

and

cerium trifluoride Cerium(III) fluoride (or cerium trifluoride), CeF3, is an ionic compound of the rare earth metal cerium and fluorine. It appears as a mineral in the form of Fluocerite, fluocerite-(Ce) - a very rare mineral species related mainly to pegmatites an ...

. Both crystallize in the trigonal system. Fluocerite-(Ce) was first described (without the Ce) in 1845 from

hydrothermal Hydrothermal circulation in its most general sense is the circulation of hot water (Ancient Greek ὕδωρ, ''water'',Liddell, H.G. & Scott, R. (1940). ''A Greek-English Lexicon. revised and augmented throughout by Sir Henry Stuart Jones. with th ...

veins in

granite Granite ( ) is a coarse-grained (phanerite, phaneritic) intrusive rock, intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly coo ...

Sweden Sweden, formally the Kingdom of Sweden, is a Nordic countries, Nordic country located on the Scandinavian Peninsula in Northern Europe. It borders Norway to the west and north, and Finland to the east. At , Sweden is the largest Nordic count ...

. Fluocerite-(La) was first described in 1969 from the type locality in central

Kazakhstan Kazakhstan, officially the Republic of Kazakhstan, is a landlocked country primarily in Central Asia, with a European Kazakhstan, small portion in Eastern Europe. It borders Russia to the Kazakhstan–Russia border, north and west, China to th ...

. 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 In mathematics, physics and chemistry, a space group is the symmetry group of a repeating pattern in space, usually in three dimensions. The elements of a space group (its symmetry operations) are the rigid transformations of the pattern that ...

structure.

References

Lanthanide minerals Trigonal minerals Minerals in space group 165 Fluorine minerals {{halide-mineral-stub