Ammonium Trimolybdate, (NH₄)₂O.3MoO₃.H₂O

Ammonium Trimolybdate, (NH₄)₂O.3MoO₃.H₂O, is obtained as "warty" crystals from a solution of ordinary ammonium molybdate, by boiling, by allowing to stand for a long time, or by the addition of warm hydrochloric acid. The salt (NH₄)₂O.5MoO₃.3H₂O is also said to exist.