Manganese violet

Manganese violet is the inorganic compound called ammonium manganese(III) pyrophosphate. The formula indicates that pyrophosphate (P
2O4−
7), ammonium (NH+
4), and manganese(III) make up this solid. It is prepared by heating a mixture of Mn
2O
3, diammonium phosphate and phosphoric acid. This material is a popular inorganic pigment.