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Formula: (NH4)3Fe(SO4)3
Anhydrous sulphate
Crystal System: Trigonal
Specific gravity: 2.22 measured, 2.228 calculated
Streak: White
Colour: Colourless to white
Luminescence: No fluorescence under short wave or long wave UV
Stability: Not hygroscopic and stable in air
Environments
Localities
At the type locality, La Fossa crater, Vulcano Island, Lipari, Eolie Islands (Aeolian Islands), Metropolitan City of
Messina, Sicily, Italy, pyracmonite occurs in an active medium-temperature (~250°C) intracrater fumarole
developed on a pyroclastic breccia. It is associated with
salammoniac, kremersite and
other new sulphates and halides. It forms aggregates of colourless to white elongate hexagonal prismatic crystals up
to 0.2 mm in length.
(CM 48.2.307-313)
Pyracmonite from La Fossa - Image
At the Huron Shale burn site, Huron River, Huron County, Ohio, USA, pyracmonite occurs as a sublimate from a
natural fire in an oil-bearing shale. Associated minerals include
sabieite, tschermigite and
voltaite
(HOM).
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