Osakaite exhibited at the Mining Museum of Akita University — Photo: 掬茶 · CC BY-SA 4.0
Osakaite
Osakaite is an IMA-recognized mineral species in the sulfate class, with the chemical formula Zn₄(SO₄)(OH)₆·5H₂O.
It crystallizes in the triclinic crystal system (space group P-1). It is a member of the Ktenasite structural group.
Key properties: Mohs hardness 1; specific gravity 2.75; White to pale blue streak; Pearly luster; optically biaxial.
IMA symbol Ok, IMA status: approved, named in 2006.
A secondary mineral on mine walls and fractures produced by reaction of oxygenated groundwater with a polymetallic sulfide deposit.
It is found associated with Hydrozincite, smithsonite, “chlorite, ” and “limonite”.
The name refers to the region (Osaka) in Japan containing the mine that produced the first specimens.