The Lyel medal is a prestigious annual scientific medal given by the Geological Society of London, equal in status to the Murchison Medal. This medal is awarded based on one Earth Scientist's exceptional contribution of research to the scientific community. It is named after Charles Lyell the Scottish geologist who demonstrated the power of known natural causes in explaining Earth's history. this example is engraved around the edge SERGEI IVANOVICH TOMKEIEFF, 1966 THE GEOLOGICAL SOCIETY, in the original leather-covered presentation case.

Professor Sergei Ivanovich Tomkeieff FRSE FGS (1892–1968) was a 20th-century Lithuanian geologist and petrologist. He was born on 20 October 1892 in Vilna the capital of Lithuania. He came to Britain either during or just after the First World War and began lecturing in Geology at Anderson College in Newcastle-upon-Tyne in 1920.

In 1948 he was elected a Fellow of the Royal Society of Edinburgh. His proposers were Arthur Holmes, James Ernest Richey, Sir Edward Battersby Bailey, Heslop Harrison, George Walter Tyrrell, John Weir, and H. B. Donald. In 1957 he became Professor of Petrology at the Anderson College.

He was author of many books including; The Tholeite Dyke at Cowgate (1953); Coals, Bitumens and other Related Fossil Carbonaceous Substances (1954); Isle of Arran (1961); The Economic Geology of Quarried Materials (1969) Dictionary of Petrology (1983) (posthumous). He was awarded the Geological Society's Lyell Medal in 1966. He died on 27 October 1968 in Newcastle aged 76