Lalondeite
Lalondeite is an IMA-recognized mineral species in the silicate class, with the chemical formula (Na,Ca)₆(Ca,Na)₃Si₁₆O₃₈(F,OH)₂·3H₂O.
It crystallizes in the triclinic crystal system (space group P-1). It is a member of the Gyrolite structural group.
Key properties: Mohs hardness 3; specific gravity 2.5; White streak; Pearly. Medium to strong, violet-blue fluorescence in MW UV; weak under SW; none under LW luster; optically biaxial.
IMA symbol Lal, IMA status: approved, named in 2002.
A late-stage low-temperature hydrothermal mineral.
It is found associated with Microcline, clinoamphibole, narsarssukite.
The mineral was named to honor Professor Andre E. Lalonde, Department of Earth Sciences, University of Ottawa, Canada, for work on mica minerals and alkaline intrusions.