They tend to form upon treatment of molybdate salts with hydrogen peroxide. Glucose boiled in an ammonium molybdate solution turns the solution blue. These metals are imported as their oxyanions, molybdate, and tungstate. Sodium molybdate, NaMoO, is useful as a source of molybdenum. Similarly, molybdate reacts in alkaline media with peroxide to form red peroxomolybdate . For this reason, fertilizers often contain small amounts of molybdate salts. Ammonium molybdate can be of different form. Powellite is a mineral form of calcium molybdate containing a small amount of tungstate. Ammonium molybdate converts to ammonium dimolybdate, which is isolated as a solid. In base, it dissolves to afford the molybdate anion. Molybdenite is purified by froth flotation, and then oxidized to form soluble molybdate. Silicate anions in solution react with molybdate anions yielding yellow silicomolybdate complexes. Molybdate chrome pigments are speciality but commercially available pigments. Sodium molybdate was first synthesized by the method of hydration. Thus molybdenum(VI) does not form , but forms the tetrahedral molybdate anion, .