Tellurite is an ion. Its chemical formula is TeO32-. They are some of the more stable tellurium compounds. They are weak oxidizing agents. In slightly acidic conditions, it makes hydrogen tellurite, HTeO3-. When it is very acidic, it makes tellurous acid. They are normally made by reacting tellurium dioxide with a metal oxide.
Tellurite is also a rare mineral. This mineral consists of tellurium dioxide. It is a yellow to white mineral. It is in areas that tend to oxidize minerals (oxidation zone). Otherwise telluride or native tellurium would be there.