Edwardsite
A rare hydrated copper-cadmium sulfate from Chile — a monoclinic secondary mineral named for mineralogist George Edwards.
Intro adapted from Wikipedia (CC BY-SA).
Edwardsite is an IMA-recognized mineral species in the sulfate class, with the chemical formula Cu₃Cd₂(SO₄)₂(OH)₆·4H₂O.
It crystallizes in the monoclinic crystal system (space group P2_1/c).
Key properties: Mohs hardness 3–3.5; specific gravity 3.53; White streak; Vitreous luster; optically biaxial.
IMA symbol Edw, IMA status: approved, named in 2009.
Found as a secondary mineral in the oxidized portion of a Ag-Pb-Zn metal deposit.
It is found associated with Niedermayrite, christelite.
The mineral was named to honor Dr. Austin Burton Edwards (1909–1960), mineralogist and petrologist in the Mineragraphic Section of the Council for Scientific and Industrial Research CSIRO).