Krennerite is an orthorhombic gold telluride mineral which can contain a relatively small amount of silver in the structure. The formula is AuTe2 varying to (Au0.8,Ag0.2)Te2. Both of the chemically similar gold-silver tellurides, calaverite and sylvanite are in the monoclinic crystal system, whereas krennerite is orthorhombic.
The color varies from silver-white to brass-yellow. It has a specific gravity of 8.53 and a hardness of 2.5. It occurs in high temperature hydrothermal environments.
Krennerite was discovered in 1878 in Sacaramb, Romania, and first described by the Hungarian mineralogist Joseph Krenner (1839–1920).
Krennerite in a quartz vein, Cresson Mine, Cripple Creek, Colorado
. Specimen size 3.0 x 2.7 x 2.5 cm. See infobox for detail photo.