Pyracmonite
Pyracmonite is an IMA-recognized mineral species in the sulfate class, with the chemical formula (NH₄)₃Fe(SO₄)₃.
It crystallizes in the hexagonal crystal system (space group R3c). It is a member of the Pyracmonite structural group.
Key properties: Mohs hardness 2; specific gravity 2.22; White streak; Vitreous luster; optically uniaxial.
IMA symbol Pyr, IMA status: approved, named in 2008.
A sublimate on pyroclastic breccia in an intercrater volcanic fumarole (~250 flC) (Italy); a sublimate from a natural fire in an oil-bearing shale (Ohio).
It is found associated with Salammonic, kremersite, (NH4)2Fe3+Cl5·H2O (Italy); sabieite, tschermigite, voltaite (Ohio).
Its name comes from the Greek for “fire” and “anvil”, in allusion to the mythical Hephaistos’s workshop, which allegedly was located on the Island of Vulcano.