Simmonsite
A sodium-lithium-aluminium fluoride first found in Nevada's Gillis Range.
Intro adapted from Wikipedia (CC BY-SA).
Simmonsite is an IMA-recognized mineral species in the halide class, with the chemical formula Na₂LiAlF₆.
It crystallizes in the monoclinic crystal system (space group P2_1/n). It is a member of the Perovskite structural group.
Key properties: Mohs hardness 2.5–3; specific gravity 3.05; White streak; Greasy luster.
IMA symbol Sim, IMA status: approved, named in 1997.
A late-stage hydrothermal mineral in a breccia pipe that cuts an amazonite-topaz- zinnwaldite pegmatite.
It is found associated with Cryolite, cryolithionite, elpasolite.
The mineral was named to honor Professor William B. Simmons (b. 1943), Professor of Mineralogy and Petrology, University of New Orleans, New Orleans, USA.