Telluride is an ion. Chemical compounds containing this ion are called tellurides. Examples are sodium telluride and hydrogen telluride. The chemical formula is Te2-. Tellurides are strong reducing agents. Some tellurides are impure, making them weaker reducing agents. Tellurides are the main source of tellurium in the ground. It only exists at very high pH. At lower pH's, hydrogen telluride, HTe-, is made. When it is acidic (very low pH), hydrogen telluride gas is made.