Kremersite is a rare mineral which is a hydrated multiple chloride of iron, ammonium and potassium with the formula: (NH₄,K)₂FeCl₅·H₂O. Kremersite is a brown-red to orange mineral that crystallizes in the orthorhombic system. It is a water-soluble mineral that is found around volcanic fumaroles. Occurs at Vesuvius, Italy and Mount Etna, Sicily. It was discovered in 1853 and named for the German chemist, Peter Kremers (born 1827).

Kremersite
Kremersite found in Russia
General
Category	Mineral
Formula (repeating unit)	(NH4,K)2FeCl5·H2O
IMA symbol	Km
Identification
Color	Ruby-red to red, brownish red
Luster	Vitreous
Diaphaneity	Translucent
Specific gravity	2.175