bastnäsitePr

Bastnäsite-(Pr) is a member of the bastnäsite mineral group, a family of rare-earth carbonate-fluoride minerals. It represents the praseodymium-dominant endmember of the series, with the general composition RECO3F, where RE denotes a light rare-earth element. In bastnäsite-(Pr), praseodymium is the principal rare-earth cation, though the structure can accommodate substitutions by other light rare earths such as lanthanum, cerium, and neodymium.

Nomenclature and composition are based on the dominant rare-earth element in the crystal. Bastnäsite-(Pr) is distinguished from other endmembers like bastnäsite-(Ce) and bastnäsite-(Nd) by the predominance of Pr over the other REEs. The mineral is named in the same way as other bastnäsite endmembers, with the suffix indicating the dominant REE.

Occurrence and environments where bastnäsite-(Pr) is found include carbonatite complexes and hydrothermal veins. It commonly occurs with minerals such as fluorite, quartz, baryte, and other rare-earth-bearing phases. The Bastnäs area in Sweden is historically significant to the bastnäsite group, aiding the naming of the mineral family, though bastnäsite-(Pr) is found in various carbonatite and hydrothermal settings worldwide.

Physical properties and appearance are typical of bastnäsite minerals: they form reasonably well-shaped crystals or radiating aggregates, have a vitreous luster, and are colorless to pale pink or yellowish. They have a white streak and a hardness around 4 on the Mohs scale, with a specific gravity in the vicinity of 4.3. Bastnäsite-(Pr) is considered a potential source of praseodymium, but bastnäsite endmembers are generally minor ore minerals compared with other REE-bearing phases.

See also: Bastnäsite, Praseodymium, Rare-earth minerals.