1) Monoclinic mineral 2) Silver mineral 
Hessite is a mineral form of disilver telluride (Ag2Te). It is a soft, dark grey telluride mineral which forms monoclinic crystals. It is named after Germain Henri Hess (1802–1850). Hessite is found in the USA in Eagle County, Colorado and in Calaveras County, California and in many other locations. Stützite (Ag7Te4) and empressite (AgTe) are r...
• (n.) A lead-gray sectile mineral. It is a telluride of silver.
(from the article `sulfide mineral`) ...and each anion surrounded by eight metal cations—is called the antifluorite structure. It is the arrangement of some of the more valuable precious ...
Hess'ite noun [ After H. Hess .] (Min.) A lead-gray sectile mineral. It is a telluride of silver. 
Silver telluride
(Silver Telluride) 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 ch...