Gordaite Field of view: 6 mm Locality: Kupferkammer Smelter, Hettstedt, Saxony-Anhalt, Germany — Photo: Henk Smeets – tomeikminerals.com · CC BY 4.0
Gordaite
A hydrated zinc-sodium sulfate-chloride named for the Sierra Gorda district of Chile.
Intro adapted from Wikipedia (CC BY-SA).
Gordaite is an IMA-recognized mineral species in the sulfate class, with the chemical formula NaZn₄(SO₄)(OH)₆Cl·6H₂O.
It crystallizes in the hexagonal crystal system (space group P-3). It is a member of the Ktenasite structural group.
Key properties: Mohs hardness 2.5; specific gravity 2.627; Vitreous to pearly luster; refractive index 1.55; optically uniaxial.
IMA symbol Gda, IMA status: approved, named in 1996.
Found in the oxidized portions of a Cu-Zn sulfide deposit (San Francisco mine, Chile); on weathered mine dumps (Helbra, Germany).
It is found associated with Zincian paratacamite, anglesite, hemimorphite, christelite, quartz (San Francisco mine, Chile); connellite, anglesite, chlorian bromargyrite (Helbra, Germany).
The name refers to the Sierra Gorda, Chile, from which the mineral was first fully characterized.