Fluoro-leakeite

minerals

astrophyllite

Formula: NaNa2(Mg2Al2Li)Si8O22F2
Inosilicate (chain silicate), amphibole group
Specific gravity: 3.14 calculated
Hardness: 6
Colour: Light greenish-blue
Environments:

Plutonic igneous environments

Fluoro-leakeite is formed by the reaction of alkaline granite with post-magmatic fluids rich in lithium and fluorine. Associated minerals include cámaraite, lithium-bearing riebeckite, aegirine and astrophyllite (HOM).

Localities

At the Verkhnee Espe Massif, Akzhaylyautas Mountains, Tarbagatai Range, East Kazakhstan, Kazakhstan, the granite is strongly altered by late-stage hydrothermal activity, with enrichment in fluorine, lithium and rare earth elements. Partial breakdown of riebeckite, aegirine, elpidite and astrophyllite was accompanied by the formation of fluoro-leakeite, polylithionite, quartz, rutile and fluorite (R&M 86.2.165).

At the type locality, Norra Kärr, Gränna, Jönköping, Jönköping County, Sweden, fluoro-leakeite occurs as isolated prismatic crystals to 2 mm long in an alkaline intrusion that mainly comprises nepheline syenite (Mindat).

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