He subsequently turned his attention to the mineralogical and stratigraphical description of the geological formations in Belgium.

[1] His Mémoire sur les terrains ardennais et rhénan de l'Ardenne, du Brabant et du Condroz (1847–1848) is notable for the care with which the mineralogy of the strata was described, but the palaeontological characterization was insufficient, and neither did he adopt the terms Silurian or Devonian.

This latter work of outstanding scholarship was one of the first serious attempts to establish the regional-scale geological correlation between the various countries of Europe.

[1] After his death, his geological map was updated by Gustave Dewalque, the successor to his professorial chair.

[1] His son, also André Dumont (1847–1920), discovered coal in the Campine basin on 1 August 1901.