Acmonidesite

Acmonidesite (NH₄,K,Pb,Na)₉Fe²⁺₄(SO₄)₅Cl₈) is a microscopic brown mineral, discovered in 2013 and described in 2019.^[1]

Acmonidesite
General
Category	Minerals
Formula	(NH4,K,Pb,Na)9Fe2+4(SO4)5Cl8
IMA symbol	Acm
Strunz classification	7.BC.
Identification
Color	Brown
Twinning	None
Cleavage	None
Fracture	None
Luster	Vitreous
Streak	Light brown
Specific gravity	2.56
Density	2.551 g/cm3
2V angle	51.6°
Dispersion	None observed

Its name comes from the mythical Greek cyclops Acmonides, said to be one of the three helpers of the god Hephaestus, the god of fire and forging, with his forge said to be located at Vulcano, also the type locality of the mineral.^[2]