The main source of tellurium is from copper anode slimes, which contain precious metals as well as various tellurides.

This is the reaction of tellurium dioxide with a base to make a tellurite salt.

Sodium tellurite improves the corrosion resistance of electroplated nickel layers.

Solutions of sodium tellurite are used for black or blue-black coatings on iron, steel, aluminum, and copper.

In microbiology, sodium tellurite can be added to the growth medium to isolate bacteria with an inherent physiological resistance to its toxicity.