Rozenite
Iron sulfate tetrahydrate — a low-humidity alteration product of melanterite on mine walls.
Intro adapted from Wikipedia (CC BY-SA).
Rozenite is an IMA-recognized mineral species in the sulfate class, with the chemical formula Fe²⁺(SO₄)·4H₂O.
It crystallizes in the monoclinic crystal system (space group P2_1/n). It is a member of the Starkeyite structural group.
Key properties: Mohs hardness 2–3; specific gravity 2.293; White streak; Vitreous luster; refractive index 1.536; optically biaxial.
IMA symbol Rzn, IMA status: approved, named in 1960.
An uncommon secondary mineral, formed at or below 21 ° C and under low humidity directly from copper-free melanterite, in turn an alteration product of pyrite or marcasite; commonly a post-mining product, in lake-bed sediments.
It is found associated with Melanterite, epsomite, jarosite, gypsum, sulfur, pyrite, marcasite, “limonite”.
The mineral was named to honor Zygmunt Rozen (1874–1936), mineralogist and petrographer, Academy of Mining and Metallurgy, Kraców, Poland.