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Achille Ernest Oscar Joseph Delesse (1817 - 1881) was a French geologist and mineralogist.

He was born in Lyceum, near Metz. At the age of twenty he entered the Ecole Polytechnique.  In 1839, he joined the French Ecole des Mines. In 1845, he was appointed to the chair of mineralogy and geology at the University in Besancon.  In 1850, was took the position of  chairman of the Department of Geology at the Sorbonne in Paris.  In 1864, he moved on to become a professor of agriculture at the Ecole des Mines and finally in 1878, he became the French inspector-general of mines.

In early years as ingénieur des mines he investigated and described various new minerals; he proceeded afterward to the study of rocks, devising new methods for their determination, and giving particular descriptions of melaphyre, arkose, porphyry, syenite, and others. Among other things, he studied the igneous rocks of the Vosges, and those of the Alps, Corsica, etc., and the subject of metamorphism. In 1858, he prepared a geological and hydrological maps of Paris, with reference to the underground water, similar maps of the départements of the Seine and Seine-et-Marne, and an agronomic map of the Seine-et-Marne (1880), in which he showed the relation that exists between the physical and chemical characters of the soil and the geological structure.

His annual Revue des progrès de géologie, undertaken with the assistance (1860-1865) of Auguste Laugel and afterwards (1865-1878) of Albert de Lapparent, was pubished from 1860 to 1880. His observations on the lithology of the deposits accumulated beneath the sea were of special interest and importance. His separate publications were: Recherches sur l'origine des roches (Paris, 1865); Étude sur le métamorphisme des roches (1869), Lithologie des mers de France et des mers principales du globe (2 vols. and atlas, 1871).