Physician, chemist and naturalist German, born in the vicinity of Pirma (Saxony) in 1765 and died in Petersburgo in 1767. His work on the origin and composition of mineral deposits and stratigraphic sedimentary rocks available contributed considerably to the development of stratigraphy.
After twenty-two years of age the title of doctorate in medicine at the University of Wittenberg, he served his profession in the city of Dresden, however, soon developed a great interest in geology and, in particular, for the disposition of mineral deposits. In 1750 the publication of their research on the composition and origin of this type of geological formations earned him recognition of the Royal Prussian Academy of Sciences in Berlin, which was named Minister of mines of the city.
Lehmann was determined that the arrangement of rocks in the Earth's surface was not random and remained a historical sequence. Based on this principle, fundamental for the development of stratigraphy, Lehmann published in 1756 the first geological cut of history, which showed a profile of the basement with the position of the strata and the location of mineral deposits. This year in response to the lithology of the German Permian system type, identified two distinct units made up of red sandstone with copper levels exploitable overlying and carbonate with evaporites rocks, named respectively with the Rotliegendes and Zechstein names.
In the Decade of 1760 he was appointed Professor of chemistry of the University of St. Petersburg and director of the imperial Museum site in the city. His research in Russia, commissioned by Catherine II, became Russian mining model until shortly after his death.