Identifying Tellurium Minerals

• Test with Sulfuric Acid. When a telluride is heated in concentrates sulfuric acid, it gives a deep crimson color to the solution. The color will disappear if the acid is heated too hot, or if after cooling it is diluted with water.
• Charcoal Test. When heated on charcoal a white sublimate of TeO2 is formed which somewhat resembles antimony oxide. It is volatile and when touché with the reducing flame gives a pale greenish color to it.
• Plaster Tablet Test. On a plaster tablet tellurium minerals when heated give a purplish brown sublimate.