Jarlite
Jarlite is an IMA-recognized mineral species in the halide class, with the chemical formula Na₂(Sr,Na)₁₄(Mg, )₂Al₁₂F₆₄(OH)₄.
It crystallizes in the monoclinic crystal system (space group C2/m). It is a member of the Jarlite structural group.
Key properties: Mohs hardness 4–4.5; specific gravity 3.87; Vitreous luster; optically biaxial.
IMA symbol Jar, grandfathered status — known before the IMA’s founding, named in 1933.
Found in vugs in a cryolite deposit with other fluorides.
It is found associated with Cryolite, gearksutite, chiolite, thomsenolite, ralstonite, prosopite, stenonite, acuminite, bøgvadite, jørgensenite, fluorite, topaz, barite.
The name refers to Carl Frederik Jarl (1872–1951), formerly President of the Danish Cryolite Company, who first noted the mineral.