Formula:
Bastnäsite-(Ce): Ce(CO3)F the most common member of the bastnäsite group
Bastnäsite-(La): La(CO3)F
Bastnäsite-(Nd): Nd(CO3)F
Bastnäsite-(Y): Y(CO3)F
All of these are anhydrous carbonates containing halogen
Bastnäsite forms oriented overgrowths and alteration pseudomorphs after fluocerite.
Crystal axes of both species oriented in parallel position
Specific gravity: 4.9 to 5.2
Hardness: 4 to 5
Streak: White
Colour: Yellow, reddish-brown; colourless to light yellow in transmitted light; bastnäsite-(Nd) may be pale purplish
pink to colourless
Solubility: Bastnäsite-(Ce) is soluble in strong, hot acids
Environments:
Pegmatites
Metamorphic environments
Bastnäsite-(Ce) occurs in contact metamorphic amphibole skarn; bastnäsite-(Nd) occurs in the outer
rim zone in crystals of bastnäsite-(Ce), found in cavities in yttrian fluorite, and
in
granite pegmatites.
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