| Emil Wilhelm Cohen | |
| Birth Date: | 12 October 1842 |
| Birth Place: | Akjär near Horsens, Jutland, Denmark |
| Death Place: | Greifswald, Germany |
| Nationality: | German |
| Fields: | Mineralogy, petrography, meteoritics |
| Known For: | A founder of modern petrography |
Emil Wilhelm Cohen (12 October 1842 – 13 April 1905) was a German mineralogist and petrographer, born in Jutland.
Cohen studied at the universities of Berlin and Heidelberg and from 1867 to 1872 was a mineralogy assistant in the latter. He then spent 18 months in South Africa, where he studied diamond and gold deposits.
Cohen devoted his following years to mineralogy and drafting descriptions of his African explorations. Through his Sammlung von Mikrophotographien zur Veranschaulichung der mikroskopischen Structur von Mineralien und Gesteinen] (1881–83; "Collection of Microphotographs on the microscopic Structure of Minerals and Rocks"),[1] he founded modern petrography.
In 1878 Cohen became professor of petrography at Strasbourg and Director of the Geological Survey for Alsace and Lorraine. In 1885 he was made professor of mineralogy at the University of Greifswald. There he started work on meteorites, one of the first mineralogists to describe the petrography of iron meteorites and their accessory minerals. Beside detecting diamonds, he isolated and analyzed an iron carbide mineral there, later named Cohenite for him.