Class : Sulfides and sulfosalts
    Subclass : Tellurides
    Crystal system : Monoclinic
    Chemistry : AuAgTe₄
    Rarity : Rare

Sylvanite is a rare telluride of gold and silver. It is a hydrothermal mineral of epithermal gold-bearing veins that accompanies native gold and other tellurides (petzite, krennerite, hessite), usually in a matrix of quartz or carbonates. Its name comes from its locality of discovery : Transylvania, and from the allusion to the first name given to the element tellurium it contains (sylvanium). Sylvanite sometimes forms prismatic crystals short according to [001] and flattened on {100}, but most often forms associations of lamellar twins resembling wedge-shaped characters, skeletal, dendritic aggregates or reticulated arborescences. On the surface, sylvanite decomposes under the action of atmospheric agents giving native gold and silver. Sylvanite is a very accessory ore of gold, tellurium and silver.

Main photo : Sylvanite from Sacaramb, Romania © Stephan Wolfsried

Twinning is common on {100}.

No fakes listed for this mineral species.