Karl Cäsar von Leonhard (12 September 1779 in Rumpenheim – 23 January 1862 in

Heidelberg Heidelberg (; Palatine German language, Palatine German: ''Heidlberg'') is a city in the States of Germany, German state of Baden-Württemberg, situated on the river Neckar in south-west Germany. As of the 2016 census, its population was 159,914 ...

) was a German

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 proce ...

and

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, althoug ...

. His son, Gustav von Leonhard, was also a mineralogist. From 1797 he studied at the universities of

Marburg Marburg ( or ) is a university town in the German federal state (''Bundesland'') of Hesse, capital of the Marburg-Biedenkopf district (''Landkreis''). The town area spreads along the valley of the river Lahn and has a population of approxima ...

and

Göttingen Göttingen (, , ; nds, Chöttingen) is a university city in Lower Saxony, central Germany, the capital of the eponymous district. The River Leine runs through it. At the end of 2019, the population was 118,911. General information The ori ...

, where

Johann Friedrich Blumenbach Johann Friedrich Blumenbach (11 May 1752 – 22 January 1840) was a German physician, naturalist, physiologist, and anthropologist. He is considered to be a main founder of zoology and anthropology as comparative, scientific disciplines. He ...

was an important influence to his career. He collected many mineralogical specimens on scientific excursions in

Saxony Saxony (german: Sachsen ; Upper Saxon: ''Saggsn''; hsb, Sakska), officially the Free State of Saxony (german: Freistaat Sachsen, links=no ; Upper Saxon: ''Freischdaad Saggsn''; hsb, Swobodny stat Sakska, links=no), is a landlocked state of ...

and

Thuringia Thuringia (; german: Thüringen ), officially the Free State of Thuringia ( ), is a state of central Germany, covering , the sixth smallest of the sixteen German states. It has a population of about 2.1 million. Erfurt is the capital and lar ...

, continued by travel to the Austrian Alps (including the

Salzkammergut The Salzkammergut (; ; bar, Soizkaumaguad, label=Central Austro-Bavarian) is a resort area in Austria, stretching from the city of Salzburg eastwards along the Alpine Foreland and the Northern Limestone Alps to the peaks of the Dachstein Mou ...

). During his journeys he made the acquaintance of

Friedrich Mohs Carl Friedrich Christian Mohs (; 29 January 1773 – 29 September 1839) was a German chemist and mineralogist. He was the creator of the Mohs scale of mineral hardness. Mohs also introduced a classification of the crystal forms in crystal syst ...

and Karl von Moll. In 1818, through assistance from Baden minister of state Sigismund von Reitzenstein, he was appointed professor of mineralogy at the

University of Heidelberg } Heidelberg University, officially the Ruprecht Karl University of Heidelberg, (german: Ruprecht-Karls-Universität Heidelberg; la, Universitas Ruperto Carola Heidelbergensis) is a public research university in Heidelberg, Baden-Württemberg, ...

. In 1807 he founded the popular mineralogical journal "''Taschenbuch für die gesammte Mineralogie''" — after 1830 the publication was known as "''Neues Jahrbuch für Mineralogie, Geologie and Paläontologie''" (edited with Heinrich Georg Bronn). He was a founding member of the ''Wetterauischen Gesellschaft'' (

Wetterau The Wetterau is a fertile undulating tract, watered by the Wetter, a tributary of the Nidda River, in the western German state of Hesse, between the hilly province Oberhessen and the north-western Taunus mountains. Bettina von Arnim writes of ...

Society). During his career, he maintained correspondence on mineralogical subjects with

Leopold von Buch Christian Leopold von Buch (26 April 1774 – 4 March 1853), usually cited as Leopold von Buch, was a German geologist and paleontologist born in Stolpe an der Oder (now a part of Angermünde, Brandenburg) and is remembered as one of the most im ...

Johann Wolfgang von Goethe Johann Wolfgang von Goethe (28 August 1749 – 22 March 1832) was a German poet, playwright, novelist, scientist, statesman, theatre director, and critic. His works include plays, poetry, literature, and aesthetic criticism, as well as t ...

Abraham Gottlob Werner Abraham Gottlob Werner (; 25 September 174930 June 1817) was a German geologist who set out an early theory about the stratification of the Earth's crust and propounded a history of the Earth that came to be known as Neptunism. While most tenet ...

and Johann Karl Wilhelm Voigt. In 1824 he introduced the term " loess" into the geological science. Nowadays Leonhard is recognized as one of one of the key pioneers of loess studies The term "leonhardite" bears his name, being defined as a partially dehydrated, opaque

laumontite Laumontite is a mineral, one of the zeolite group. Its molecular formula is , a hydrated calcium-aluminium silicate. Potassium or sodium may substitute for the calcium but only in very small amounts. It is monoclinic, space group C2/m. It forms ...

Selected works

* ''Systematisch-tabellarische Uebersicht und Charakteristik der Mineralkörper'', 1806 (with Johann Heinrich Kopp and Karl Friedrich Merz) – Systematic tabular overview and characteristics of the mineral body. * ''Bedeutung und Stand der Mineralogie'', 1816 – The importance and state of mineralogy. * ''Mineralogisch-chemische Untersuchungen des Triphan's und Tantalit's'', 1818 – Mineralogical-chemical studies of triphane and

tantalite The mineral group tantalite Fe,_manganese.html"_;"title="iron.html"_;"title="iron">Fe,_manganese">Mn)Tantalum">Ta2oxygen.html" ;"title="manganese">Mn)Tantalum.html" ;"title="iron">Fe,_manganese.html" ;"title="iron.html" ;"title="iron">Fe, manga ...

. * ''Handbuch der oryktognosie'', 1821 – Handbook of mineralogy. *''Charakteristik der Felsarten'', 1824 – a catalogue of ground materials. * ''Die Basalt-Gebilde in ihren Beziehungen zu normalen und abnormen Felsmassen'', 1832 –

Basalt Basalt (; ) is an aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the surface of a rocky planet or moon. More than 90 ...

formations in their relationship to normal and abnormal masses of rock. * ''Naturgeschichte des mineralreichs'' (2 volumes, 1833) – Natural history of the mineral kingdom. * ''Lehrbuch der geognosie und geologie'', 1835 – Textbook of

geognosy Abraham Gottlob Werner (; 25 September 174930 June 1817) was a German geologist who set out an early theory about the stratification of the Earth's crust and propounded a history of the Earth that came to be known as Neptunism. While most tene ...

and geology. * ''Geologie, oder Naturgeschichte der Erde'' (5 volumes, 1836) – Geology; natural history of the Earth. * ''Agenda geognostica; Hülfsbuch für reisende Gebirgsforscher und Leitfaden zu Vorträgen über angewandte Geognosie'', 1838 – Geognostic agenda; hülfsbuch for mountain researchers and a guide to lectures on applied geology.

References

{{DEFAULTSORT:Leonhard, Karl Casar von 1779 births 1862 deaths People from Offenbach am Main University of Marburg alumni University of Göttingen alumni Academic staff of Heidelberg University 19th-century German geologists German mineralogists Members of the Göttingen Academy of Sciences and Humanities