Billwiseite
A very rare oxide found at the Stak Nala pegmatite near Toghla village in Gilgit-Baltistan, Pakistan.
Intro adapted from Wikipedia (CC BY-SA).
Billwiseite is an IMA-recognized mineral species in the tungstate class, with the chemical formula Sb³⁺₅Nb₃WO₁₈.
It crystallizes in the monoclinic crystal system (space group C2/c).
Key properties: Mohs hardness 5; specific gravity 6.33; Colorless to very pale yellow streak; Vitreous luster.
IMA symbol Bwi, IMA status: approved, named in 2010.
Found in a complex zoned granitic pegmatite of the LCT (Li–Cs–Ta) type.
It is found associated with Lepidolite, B-rich muscovite.
The mineral was named to honor William Stewart Wise (b. 1933), Professor of Geology Emeritus, University of California at Santa Barbara, USA.