Biraite-(La)
Biraite-(La) is an IMA-recognized mineral species in the silicate class, with the chemical formula La₂Fe²⁺(CO₃)(Si₂O₇).
It crystallizes in the monoclinic crystal system (space group P2_1/c). It is a member of the Biraite structural group.
Key properties: Mohs hardness 5; specific gravity 4.682; White streak; Vitreous luster; optically biaxial.
IMA symbol Bia-La, IMA status: approved, named in 2020.
Formed in polymineralic nodules by metasomatism of primary bastnäsite-(La)/-(Ce) of probable alkaline pegmatitic origin.
It is found associated with Allanite-(Ce)/-(La), bastnäsite-(Ce)/-(La), fluorbritholite-(Ce), perbøeite-(Ce)/-(La), percleveite-(Ce)/-(La), törnebohmite-(Ce)/-(La).
Suffix indicates the lanthanum analog of biraite-(Ce).
Index entry. This entry combines official IMA/RRUFF species data with published physical-property data — a full written entry hasn’t been published yet.
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