Petzite with quartz - Sacarîmb (Sãcãrâmb; Szekerembe; Nagyág), Hunedoara Co., Romania (xx>1mm) — Photo: Didier Descouens · CC BY-SA 3.0
Petzite
A soft steel-gray silver-gold telluride of hydrothermal veins, often with other rare tellurium minerals.
Intro adapted from Wikipedia (CC BY-SA).
Petzite is an IMA-recognized mineral species in the sulfide class, with the chemical formula Ag₃AuTe₂.
It crystallizes in the cubic crystal system (space group I4_132).
Key properties: Mohs hardness 2.5–3; specific gravity 8.7–9.4; steel-gray streak; Metallic. Anisotropism: Noticeable in part. R: (400) 45.0, (420) 43.7, (440) 42.4, (460) 41.4, (480) 40.6, (500) 39.9 luster.
IMA symbol Ptz, grandfathered status — known before the IMA’s founding, named in 1845.
With other tellurides in vein-controlled gold deposits.
It is found associated with Gold, hessite, sylvanite, krennerite, calaverite, altaite, montbrayite, melonite, frohbergite, tetradymite, rickardite, vulcanite, pyrite.
The name commemorates W. Petz, who first analyzed the mineral.