Jørgensenite

jorgensenite

jarlite

cryolite

gearksutite

Images

Formula:Na₂Sr₁₄Na₂Al₁₂F₆₄(OH)₄
Fluoride
Crystal System: Monoclinic
Specific gravity: 3.89 measured, 3.94 calculated
Hardness: 3½ to 4
Streak: White
Colour: Colourless
Environments

Pegmatites

Jørgensenite is a very rare aluminofluoride reported from only one locality to date (March 2021).

Localities

The type locality is the Ivigtut cryolite deposit, Ivittuut, Arsuk Fjord, Sermersooq, Greenland, Denmark. Here jørgensenite occurs in fissure fillings within the main cryolite mass, and in crystal-lined cavities containing aggregates up to 2 mm across of jørgensenite overgrown by jarlite. It also occurs as grains up to l0 mm across with stenonite (CM 35.175-179).
Other associated minerals include thomsenolite, gearksutite, topaz and muscovite (HOM).

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