A study on the endothermic peak of transformation of the pyrolusite was made by using differential thermal curves for analytical reproducibility, and it was done in quantity on range from 50 mg to 450 mg of pyrolusite species. The separation of ${alpha}-MnO_2$ peak was impossible due to the overlapping between $alpha$ and pyrolusite peaks, and the pyrolusite was determined among the species, ${gamma}-MnO_2$ and ${delta}-MnO_2$, with an error ranging from $5{\%}$ to $10{\%}$.