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Download hereGENERAL DESCRIPTION
Bastnäsite-(Ce) is a cerium, lanthanum fluorocarbonate containing also a certain number of other Rare-Earths elements (such as neodymium) as well as yttrium. It is formed in syenites and pegmatites.
Its crystals are transparent, with a lemon-yellow, yellow-to-brown reddish color. Crystals are tabular with a hexagonal shape and sometimes overlapping themselves. They can be large-sized (30 to 40 cm).
Bastnäsite is associated other minerals containing of Rare-Earths elements, such as synchysite-(Ce) or monazite but also calcite, natrolite and many other minerals.
The deposits producing beautiful crystals are not numerous : for example: the Malosa mount in Malawi (crystals of 1 cm), the Saint-Peter dome area in Colorado (USA) with crystals of 2,5 cm or Sweden, Madagascar and China. Recently, beautiful clusters of crystals, sometimes gemmeous, were found in Pakistan (Zagi Mountains).
Beautiful prismatic crystals of approximately 1,5 cm in length arise from the talc quarry of Trimouns in Ariège.
The type is preserved at Naturhistoriska riksmuseet of Stockholm in Sweden.
Did you know? Bastnäsite is, with monazite, one of the principal sources of cerium. Cerium is used for self-cleaning ovens, to discolor glasses and to synthesize various gasoline products in oil industry.
HISTORY : Named after its type-locality : Bastnäs
Species described in 1838 by Wilhelm Hisinger (1766-1852), Swedish chemist who discovered with Martin Klaproth and Jöns Berzélius, the element cerium (Ce)
Type-locality : mines Bastnäs, district de Ridarhyttan, Vdstmanland, Suède
ANCIENT NAME : Basicerine, fluocerine, hamartite, basiskt fluor-cerium
CHEMICAL FORMULA : (Ce, La,Y) CO3F
CRYSTAL SYSTEM : Hexagonal
COLOR : White, gray, brown, yellow, rose
DIAPHANIETY : Transparent to opaque
LUSTER : Vitreous
STREAK : White
MORPHOLOGIE : Small prismatic crystals, hexagonal, rosette
HARDNESS : 4,0-4,5
CHEMICAL CLASS: 4,7-5,0
DENSITY : V - Carbonates, nitrates
GROUP : Bastnäsite
STRUNZ CLASS BEFORE 2001 : 5/C.07-30
STRUNZ CLASS AFTER 2001 : 5.DB.35
