Jarlite

halide

thomsenolite

Formula: Na2(Sr,Na)14(Mg,☐)2Al12F64(OH)4
Halide
Specific gravity: 3.78 to 3.93
Hardness: 4 to 4½
Streak: White
Colour: Colourless, grey-white, white; colourless in transmitted light.
Solubility: Soluble in AlCl3 solution; easily fusible, with effervescence (Dana).
Environments

Pegmatites

At the type locality, the Ivigtut Cryolite deposit, Sermersooq, Greenland, Denmark, jarlite occurs growing with thomsenolite in vugs in a pegmatitic cryolite deposit in granite. Associated minerals include cryolite, gearksutite, chiolite, thomsenolite, hydrokenoralstonite, prosopite, stenonite, acuminite, bøgvadite, jørgensenite, fluorite, topaz and baryte (AM 34.383, Dana, Mindat, Webmin, HOM).

Common impurities: Ca

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