“Its flakes and nuggets are usually pure, besides a few odd alloys. The exception, the single element that will bond to gold, is tellurium, a vampirish element first isolated in Transylvania in 1782. Tellurium combines with gold to form some garish - sunding minerals - krennerite, petzite, sylvanite, and calaverite -- with some qually atrocious chemical formulas.”
Every element can bond with another element to form a compound, but gold is an outsider. Gold has many functions and several gold complexes have been applied to treat rheumatoid arthritis, a disease that make the tissue that the inside of joints to thicken, resulting in swelling and pain in and around the joints. Generally speaking, gold is not very reactive. It does not combine with oxygen or dissolve in most acids. Since gold is the only metal that is found in nature in the metallic state, it does not blend with most elements. Additionally, gold is considered as a noble metal, it can’t react with other elements easily, because the noble metals are a group of metals that resist oxidation and corrosion in moist air. Noble metals are placed in the d-block of the modern periodic table, there are some elements with completely filled d-orbitals, one of them is gold. Noble metals are the most non-reactive metals, they are insoluble in acid, base and even water. They are not easily attacked by acids and they are the opposite of the base metals, which are more readily oxidize and corrode.
Since gold commonly occurs as a native metal, it does not combine with other elements, but it will form compounds (or minerals) with tellurium, sulfur, or selenium. Calaverite, or gold telluride, is an uncommon telluride of gold, a metallic mineral with the chemical formula AuTe2.
Gold telluride ores are important gold refractory ores due to the presence of sulfides and other gangue materials. Flotation procedures are much easier for gold tellurides compared to other refractory gold-bearing ores. For the conventional cyanide leaching process, pretreatment such as oxidation is required to achieve high gold recovery. Roasting gold telluride is relatively simple but not an environment-friendly method; the smoke that was burned out will concentrate in the air for human to breathe in, and the charcoal will make the environment worse. Bio-oxidation technology seems to be more suitable for the oxidation of flotation concentrate. Other treatment methods involve cyanide leaching, thiourea leaching, ammoniacal thiosulfate leaching, carbon-in-pulp, and resin-in-pulp. Also gold telluride is corrosion resistant, highly conductive, highly ductile, and non-toxic, so it is used in electronic connections and switches.
