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.