Henry Clifton Sorby

Born May 10, 1826, in Wood-bourne, near Sheffield, Great Britain; died Mar. 9,1908, in Sheffield. British naturalist and petrographer. Member of the Royal Society of London (1857; president in the years 1878–80).

Sorby developed a microscopic technique for use in petrography and in 1849 was the first to propose the preparation of thin sections of minerals and rocks for investigating them under a microscope in transmitted light. He investigated various liquid inclusions in minerals and in 1858 demonstrated the possibility of determining the formation temperature of minerals from the inclusions (thermometric method). Sorby also investigated the nature of the isomorphism and coloration of minerals, and with the aid of spectral analysis and the microscope he studied the material composition of meteorites. He conducted experiments to determine the conditions necessary for the formation of cleavage and showed that cleavage is a consequence of pressure. Sorby received an honorary doctorate from Cambridge University in 1879.