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Formula: KNaSiF6
Silicofluoride
Crystal system: Orthorhombic
Specific gravity: 2.69 calculated
Streak: White
Colour: Colourless
Luminescence: Not fluorescent under UV
Radioactivity: barely detectable
Environments
Heklaite occurs as a sublimate precipitated around fumaroles emitting F-rich volcanic gases. Associated
minerals include hydrokenoralstonite,
malladrite, hieratite and
jakobssonite
(HOM).
Localities
At the type locality, Hekla, Rangárþing ytra, Southern Region, Iceland, heklaite was found among fumarolic
encrustations collected in 1992 on the Hekla volcano. It forms a fine-grained mass of micron- to sub-micron-sized
crystals intimately associated with malladrite,
hieratite and
hydrokenoralstonite. Heklaite is colourless, transparent
and non-fluorescent, with a vitreous lustre and a white streak.
(MM 74.1.147–157).
Type locality heklaite is the natural product of hydrofluoric acid-bearing volcanic fumarole gases reacting
with feldspar in volcanic rock
(Mindat).
At Central Florida Phosphate Mining District, Polk County, Florida, USA, fine heklaite crystals are an
accidentally formed anthropogenic compound in gypsum industrial waste
piles, a product of reaction between clay minerals and the
hydrofluoric acid-rich by-products of superphosphate fertiliser production
(Mindat).
Heklaite from Polk County -
Image
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