Pentti Eskola

Pentti Elias Eskola was a Finnish petrologist born January 8, 1883, in Honkilahti, Finland, who died December 6, 1964, in Helsinki, at age 81, and who graduated from the University of Helsinki in 1906, earned his doctorate there in 1914, became a geologist for the Geological Survey of Finland in 1922, and served as professor of geology at Helsinki from 1924 to 1954. He specialized in the petrology of granites, and his major achievement was developing the concept of metamorphic facies, a classification method for rock formation under varying pressure and temperature that remains foundational to petrology; his approach was shaped by the research of Jakob Sederholm, which he encountered at age 23. He received the Penrose Medal in 1951, the Wollaston Medal in 1958, and the Vetlesen Prize in 1964, and was honored with a state funeral upon his death; the mineral eskolaite is named for him.