Achille Ernest Oscar Joseph Delesse (3 February 181724 March 1881) was a French

geologist A geologist is a scientist who studies the solid, liquid, and gaseous matter that constitutes Earth and other terrestrial planets, as well as the processes that shape them. Geologists usually study geology, earth science, or geophysics, althou ...

and

mineralogist Mineralogy is a subject of geology specializing in the scientific study of the chemistry, crystal structure, and physical (including optical) properties of minerals and mineralized artifacts. Specific studies within mineralogy include the proces ...

. He is credited for inventing the Delesse principle in

stereology Stereology is the three-dimensional interpretation of two-dimensional cross section (geometry), cross sections of materials or tissues. It provides practical techniques for extracting quantitative information about a three-dimensional material from ...

Education and career

Delesse was born at

Metz Metz ( , , lat, Divodurum Mediomatricorum, then ) is a city in northeast France located at the confluence of the Moselle and the Seille rivers. Metz is the prefecture of the Moselle department and the seat of the parliament of the Grand E ...

. At the age of twenty he entered the

École Polytechnique École may refer to: * an elementary school in the French educational stages normally followed by secondary education establishments (collège and lycée) * École (river), a tributary of the Seine flowing in région Île-de-France * École, Savoi ...

, and subsequently went to the Ecole des Mines, where he was trained under the tutelage of

Jean-Baptiste Élie de Beaumont Jean-Baptiste Armand Louis Léonce Élie de Beaumont (25 September 1798 – 21 September 1874) was a French geologist. Biography Élie de Beaumont was born at Canon, in Calvados. He was educated at the Lycee Henri IV where he took the fir ...

and

Ours-Pierre-Armand Petit-Dufrénoy Ours-Pierre-Armand Petit-Dufrénoy (5 September 1792 – 20 March 1857) was a French geologist and mineralogist. Life He was born at Sevran, in the ''département'' of Seine-et-Oise. After leaving the Imperial Lyceum in 1811, he studied until 1 ...

. In 1845, he was appointed to the chair of

mineralogy Mineralogy is a subject of geology specializing in the scientific study of the chemistry, crystal structure, and physical (including optical) properties of minerals and mineralized artifacts. Specific studies within mineralogy include the proces ...

and

geology Geology () is a branch of natural science concerned with Earth and other astronomical objects, the features or rocks of which it is composed, and the processes by which they change over time. Modern geology significantly overlaps all other Ear ...

at the

University of Franche-Comté The University of Franche-Comté (UFC) is a pluridisciplinary public French university located in Besançon, Franche-Comté, with decentralized campuses in Belfort, Montbéliard, Vesoul and Lons-le-Saunier. It is a founding member of the comm ...

Besançon Besançon (, , , ; archaic german: Bisanz; la, Vesontio) is the prefecture of the department of Doubs in the region of Bourgogne-Franche-Comté. The city is located in Eastern France, close to the Jura Mountains and the border with Switzerl ...

. In 1850, he became the chair of geology at the

Sorbonne Sorbonne may refer to: * Sorbonne (building), historic building in Paris, which housed the University of Paris and is now shared among multiple universities. *the University of Paris (c. 1150 – 1970) *one of its components or linked institution, ...

Paris Paris () is the capital and most populous city of France, with an estimated population of 2,165,423 residents in 2019 in an area of more than 105 km² (41 sq mi), making it the 30th most densely populated city in the world in 2020. S ...

; and in 1864, professor of

agriculture Agriculture or farming is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled people to ...

at the Ecole des Mines. Delesse died in Paris on 24 March 1881.

Research

In early years as ''ingénieur des mines'', Delesse investigated and described various new

mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. ( ...

s; he proceeded afterward to the study of

rock Rock most often refers to: * Rock (geology), a naturally occurring solid aggregate of minerals or mineraloids * Rock music, a genre of popular music Rock or Rocks may also refer to: Places United Kingdom * Rock, Caerphilly, a location in Wales ...

s, devising new methods for their determination, and giving particular descriptions of melaphyre,

arkose Arkose () or arkosic sandstone is a detrital sedimentary rock, specifically a type of sandstone containing at least 25% feldspar. Arkosic sand is sand that is similarly rich in feldspar, and thus the potential precursor of arkose. Quartz is c ...

, porphyry,

syenite Syenite is a coarse-grained intrusive igneous rock with a general composition similar to that of granite, but deficient in quartz, which, if present at all, occurs in relatively small concentrations (< 5%). Some syenites contain larger proport ...

, and others. The

igneous rock Igneous rock (derived from the Latin word ''ignis'' meaning fire), or magmatic rock, is one of the three main The three types of rocks, rock types, the others being Sedimentary rock, sedimentary and metamorphic rock, metamorphic. Igneous rock ...

s of the

Vosges The Vosges ( , ; german: Vogesen ; Franconian and gsw, Vogese) are a range of low mountains in Eastern France, near its border with Germany. Together with the Palatine Forest to the north on the German side of the border, they form a single ...

, and those of the

Alps The Alps () ; german: Alpen ; it, Alpi ; rm, Alps ; sl, Alpe . are the highest and most extensive mountain range system that lies entirely in Europe, stretching approximately across seven Alpine countries (from west to east): France, Sw ...

Corsica Corsica ( , Upper , Southern ; it, Corsica; ; french: Corse ; lij, Còrsega; sc, Còssiga) is an island in the Mediterranean Sea and one of the 18 regions of France. It is the fourth-largest island in the Mediterranean and lies southeast of ...

, etc., and the subject of

metamorphism Metamorphism is the transformation of existing rock (the protolith) to rock with a different mineral composition or texture. Metamorphism takes place at temperatures in excess of , and often also at elevated pressure or in the presence of chem ...

occupied his attention. He also prepared in 1858 geological and hydrological maps of Paris, with reference to the underground water, similar maps of the ''

département In the administrative divisions of France, the department (french: département, ) is one of the three levels of government under the national level ("territorial collectivity, territorial collectivities"), between the regions of France, admin ...

s'' of the

Seine ) , mouth_location = Le Havre/Honfleur , mouth_coordinates = , mouth_elevation = , progression = , river_system = Seine basin , basin_size = , tributaries_left = Yonne, Loing, Eure, Risle , tributarie ...

and

Seine-et-Marne Seine-et-Marne () is a Departments of France, department in the Île-de-France Regions of France, region in Northern France. Named after the rivers Seine and Marne (river), Marne, it is the region's largest department with an area of 5,915 square ...

, 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 Soil, also commonly referred to as earth or dirt, is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Some scientific definitions distinguish ''dirt'' from ''soil'' by restricting the former te ...

and the geological structure. The annual ''Revue des progrès de géologie'' of Delesse, undertaken with the assistance (1860–1865) of Auguste Laugel and afterwards (1865–1878) of

Albert de Lapparent Albert Auguste Cochon de Lapparent (30 December 18395 May 1908) was a French geologist. Life He was born at Bourges. After studying at the École polytechnique from 1858 to 1860 he became ''ingénieur au corps des mines'', and took part in draw ...

, was carried on from 1860 to 1880. His observations on the

lithology The lithology of a rock unit is a description of its physical characteristics visible at outcrop, in hand or core samples, or with low magnification microscopy. Physical characteristics include colour, texture, grain size, and composition. Lit ...

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).

Honors

Delesse was elected as a member to the

American Philosophical Society The American Philosophical Society (APS), founded in 1743 in Philadelphia, is a scholarly organization that promotes knowledge in the sciences and humanities through research, professional meetings, publications, library resources, and communit ...

in 1863, and to the

French Academy of Sciences The French Academy of Sciences (French: ''Académie des sciences'') is a learned society, founded in 1666 by Louis XIV of France, Louis XIV at the suggestion of Jean-Baptiste Colbert, to encourage and protect the spirit of French Scientific me ...

in 1879. In 1878, he became inspector-general of the

Corps des mines The ''Corps des mines'' is the foremost technical Grand Corps of the French State (grands corps de l'Etat). It is composed of the state industrial engineers. The Corps is attached to the French Ministry of Economy and Finance. Its purpose is to e ...

References

{{DEFAULTSORT:Delesse, Achille French geologists French mineralogists Members of the French Academy of Sciences 1817 births 1881 deaths Academic staff of the University of Paris École Polytechnique alumni People from Metz Mines Paris - PSL alumni University of Franche-Comté people