Sulfate, a compound composed of sulfate ions (SO42-) and other metal ions, is an electrolyte, and most of them are soluble in water. Sulfate minerals are salts formed by the combination of metal cations (including ammonium) and sulfate. As sulfur is a variable valence element, it can form different minerals in different valence states in nature. When it combines with four O2- ions in the highest valence state S6+ to form SO42-, it will form sulfate with metal cations. Among sulfate minerals, there are more than twenty kinds of metal cations combined with sulfate. That is to say, there is a salt containing sulfate, that is, sulfate.