Fluorluanshiweiite
Fluorluanshiweiite is an IMA-recognized mineral species in the silicate class, with the chemical formula KLiAl₁.₅ ₀.₅(Si₃.₅Al₀.₅)O₁₀F₂.
It crystallizes in the monoclinic crystal system (space group C2/m). It is a member of the Mica structural group.
Key properties: Mohs hardness 3; specific gravity 2.94; White streak; Vitreous, pearly on cleavage surfaces luster; optically biaxial.
IMA symbol Flw, IMA status: approved, named in 2019.
Found in a Li-Cs-Ta granitic pegmatite deposit formed in the late stage of the evolution of the pegmatite-forming magmatic liquid.
It is found associated with Luanshiweiite, polylithionite, cookeite, albite, quartz, spodumene, montebrasite, elbaite, fluorapatite, pollucite, nanpingite, tantalite-(Mn), columbite-(Mn).
The prefix indicates the F-dominant at the A site analogue of luanshiweiite. Can be described also as the K-dominant at the I site analogue of voloshinite.