Identifying Phosphorus Minerals

1. Precipitation with Ammonium Molybdate. Phosphorus exists in minerals in the from of phosphoric acid in the phosphates. It is best tested for by form in a dilute nitric acid solution of the mineral and adding a few cubic centimeters of this to an excess of ammonium molybdate solution. A canary-yellow precipitate forms slowly at first and comes down best in warm solution.
2. Flame Test. Many phosphates when heated before the blowpipe give a pale bluish green flame color. This may frequently be obtained better when the mineral has previously been moistened with a drop of concentrated sulfuric acid.