Petzite

For other uses, see Telluric silver.

The mineral petzite, Ag₃AuTe₂, is a soft, steel-gray telluride mineral generally deposited by hydrothermal activity. It forms isometric crystals, and is usually associated with rare tellurium and gold minerals, often with silver, mercury, and copper.

Petzite
Petzite with quartz – Sacarîmb, Nagyág, Romania
General
Category	telluride mineral
Formula	Ag3AuTe2
IMA symbol	Ptz[1]
Strunz classification	2.BA.40a
Crystal system	Cubic
Crystal class	Gyroidal (432) (same H-M symbol)
Space group	I4132
Identification
Color	Steel-gray to iron-black, commonly tarnished from bronze-yellow to sooty black; grayish white with a pale bluish tint in polished section
Crystal habit	Granular to massive
Fracture	Subconchoidal irregular
Tenacity	Slightly sectile to brittle.
Mohs scale hardness	2.5 – 3
Luster	Metallic
Streak	Grayish black
Diaphaneity	Opaque
Specific gravity	8.7 – 9.14
References	[2][3][4][5]

The name comes from chemist W. Petz, who first analyzed the mineral from the type locality in Săcărâmb, Transylvania, Romania in 1845. It was described by Wilhelm Karl Ritter von Haidinger in 1845 and dedicated to W. Petz who had carried out the first analyses.^[3][4]

It occurs with other tellurides in vein gold deposits. It is commonly associated with native gold, hessite, sylvanite, krennerite, calaverite, altaite, montbrayite, melonite, frohbergite, tetradymite, rickardite, vulcanite and pyrite.^[3]

Petzite forms together with uytenbogaardtite (Ag₃AuS₂) and fischesserite (Ag₃AuSe₂) the uytenbogaardtite group.

See also

• List of minerals
• List of minerals named after people