A selenate selenite is a chemical compound or salt that contains selenite and selenate anions (SeO<sub>3</sub><sup>2-</sup> and SeO<sub>4</sub><sup>2-</sup>). These are mixed anion compounds. Some have third anions.
A selenate selenite compound may also be called a selenite selenate.
One way to produce a selenate selenite compound is to evaporate a water solution of selenate and selenite compounds.
On heating, selenate selenites lose SeO<sub>2</sub> and O<sub>2</sub> and yield selenites, and ultimately metal oxides.
Related to these are the sulfate sulfites and tellurate tellurites. They can be classed as mixed valent compounds.