(also Gustav Tschermak von Seysenegg). Born Apr. 19,1836, in Littau, near Olomouc; died May 4, 1927, in Vienna. Austrian mineralogist and petrographer. Member of the Academy of Sciences in Vienna (1875).
Tschermak graduated from the University of Vienna. In 1860 he received the Ph. D. degree from the University of Tübingen. In 1861 he began teaching at the University of Vienna, where he was a professor from 1868 to 1906. From 1868 to 1877 he was director of the imperial mineral collection at the University of Vienna. Tschermak’s major works dealt with the mineralogy of complex silicates, including feldspars, pyroxenes, amphiboles, chlorites, and micas. Tschermak clarified the dual role of aluminum in silicates and studied the phenomenon of isomorphism. He investigated meteorites and proposed a theory of their origin, according to which meteorites were formed during volcanic eruptions on asteroids. Tschermak was the author of Lehrbuch der Mineralogie (1881) and the founder of a journal later named after him, Tschermaks mineralogische und petrographische Mitteilungen, first published in 1871.
Tschermak was an honorary member of the St. Petersburg Academy of Sciences (1912). A hypothetical silicate found in pyroxenes (augites) has been named after him.