THE MINERAL HESSITE

Chemistry: Ag₂Te, Silver Telluride.
Class: Sulfides.
Subclass: Tellurides.
Uses: As mineral specimens and as a very minor ore of silver and tellurium.
Specimens

Hessite is named after the nineteenth century Swiss chemist and Professor of St. Petersburg Mining Institute, Germain Henry Hess. He was the first to analyze specimens of this mineral, some of which were recovered by Gustav Rose in 1829. A synonym of hessite is "silver telluride" which is chemically accurate but is not very mineral like.

Hessite is a telluride mineral, a special group of minerals to collectors. Other tellurides include altaite, a lead telluride; calaverite, a gold telluride; coloradoite, a mercury telluride; empressite, another silver telluride; kostovite, a copper gold telluride; krennerite, a silver gold telluride; melonite, a nickel telluride; petzite, a silver gold telluride; rickardite, a copper telluride and sylvanite, a silver gold telluride. The fondness of tellurium for the precious metals of gold, silver and copper is quite obvious in the preceeding list. Hessite in fact is often found with native gold and native silver. The elemental metal tellurium is also found associated with hessite.

Hessite is generally gray in color and forms pseudo-cubic crystals despite being monoclinic. Its ability to be cut by a knife or its sectility is diagnostic as well as its associations. Hessite is found in hydrothermal veins with the associated minerals mentioned above.

PHYSICAL CHARACTERISTICS:

Color is a steel gray to lead gray.
Luster is metallic.
Transparency: Crystals are opaque.
Crystal System: Monoclinic; 2.
Crystal Habits include pseudo-cubic to prismatic crystals; fibrous and massive forms are also known.
Cleavage: Indistinct in one direction.
Fracture: Uneven.
Hardness is 1.5 - 2
Specific Gravity is 8.2 - 8.3 (much heavier than average for metallic minerals)
Streak is gray.
Other Characteristics: Specimens are sectile.
Associated Minerals include gold, quartz, altaite, petzite, sylvanite, chlorargyrite, chlorite, keystoneite, silver, tellurium, coloradoite, thalcusite, tetradymite, sphalerite, chalcopyrite, pyrite, galena and other sulfides.
Notable Occurrences include the type locality of Sacaramb (nagyag), Transylvania, Romania as well as San Sebastian and Jalisco, Mexico; Zavodinsk Mine, Altai Mountains, Kazakhstan; Mont Saint-Hilaire, Quebec, Canada and in the United States: Tierra Blanca, Sierra County, New Mexico; Calaveras, Nevada; Cash Mine, Boulder County and Cripple Creek, Colorado; Ross Hannibal Mine, Lawrence County, South Dakota; Tombstone, Arizona; the McAlpine Mine, Tuolumne County and Carson Hill, Calaveras County, California; Eureka Standard Mine, Utah County, Utah and the Flambeau Copper Mine, Ladysmith, Wisconsin.
Best Field Indicators are crystal habit, locality, color, sectility, lack of good cleavage, softness and density.