Acmonidesite
A microscopic brown sulfate-chloride named for Acmonides, a mythological cyclops said to work the forge at Vulcano — the mineral's type locality.
Intro adapted from Wikipedia (CC BY-SA).
Acmonidesite is an IMA-recognized mineral species in the sulfate class, with the chemical formula (NH₄,K,Pb,Na)₉Fe²⁺₄(SO₄)₅Cl₈.
It crystallizes in the orthorhombic crystal system (space group C222_1).
Key properties: specific gravity 2.56; Light brown streak; Vitreous luster; optically biaxial.
IMA symbol Acm, IMA status: approved, named in 2013.
A fumarolic sublimate on pyroclastic breccia.
It is found associated with Salammoniac, alunite, adranosite.
The name refers to Acmonides one of Ovidius’ Cyclops, helpers of Hephaistos, the mythological god of fire whose forge was alleged to be located at Vulcano.