Ammonium heptamolybdate

Ammonium heptamolybdate is the inorganic compound, normally encountered as the tetrahydrate, whose chemical formula is (NH4)6Mo7O24·4H2O. It is a colorless solid, often referred to as ammonium paramolybdate or simply as ammonium molybdate, although "ammonium molybdate" can also refer to ammonium orthomolybdate, (NH4)2MoO4, and several other compounds. Potassium heptamolybdate, also obtained as the tetrahydrate, is very similar to the ammonium salt.