Thomsenolite found in Ivittuut, Greenland — Photo: Kritzolina · CC BY-SA 4.0
Thomsenolite
A hydrated sodium-calcium aluminium fluoride — an alteration product of cryolite from Ivigtut, Greenland.
Intro adapted from Wikipedia (CC BY-SA).
Thomsenolite is an IMA-recognized mineral species in the halide class, with the chemical formula NaCaAlF₆·H₂O.
It crystallizes in the monoclinic crystal system (space group P2_1/c).
Key properties: Mohs hardness 2; specific gravity 2.981; Vitreous, pearly on cleavages luster; optically biaxial.
IMA symbol Tse, grandfathered status — known before the IMA’s founding, named in 1868.
Occurs as an alteration product of cryolite and other alkali aluminum fluorides, most commonly in granite pegmatites.
It is found associated with Cryolite, pachnolite, ralstonite, chiolite, cryolithionite, elpasolite, sellaite, fluorite.
The mineral was named to honor Hans Peter Jörgen Julius Thomsen (1826–1909), Danish physical chemist, who founded the Danish cryolite industry and first noted the species.