Stetefeldtite and Stephanite from Belmont, Nevada, USA — Photo: Kritzolina · CC BY-SA 4.0
Stetefeldtite
A silver-bearing antimonate of the roméite group — a disputed or poorly characterized species.
Intro adapted from Wikipedia (CC BY-SA).
Stetefeldtite is an IMA-recognized mineral species in the oxides & hydroxide class, with the chemical formula Ag₂Sb₂(O,OH)₇.
It is a member of the Pyrochlore structural group.
Key properties: Mohs hardness 3.5–4.5; specific gravity 4.6; Pale yellow, shining streak.
IMA symbol Sf, IMA status: questionable, named in 1867.
Apparently an alteration product in the oxidized zone of some hydrothermal Ag–Sb-bearing mineral deposits, where it may constitute an ore of silver.
It is found associated with Chalcocite, pyrite, quartz (Belmont, Nevada, USA).
The mineral was named to honor Carl August Stetefeldt (1838–1896), German-American mining engineer and metallurgist.