Kathleen Lonsdale (1903-1971) was an early pioneer of X-ray crystallography, a field primarily concerned with studying the shapes of organic and inorganic molecules.

In 1929, Kathleen Lonsdale was the first to prove experimentally that the hexamethylbenzene crystal, an unusual form of the aromatic compound, was both hexagonal and flat in shape. In 1931, she was the first to use Fourier analysis to illustrate the structure of hexachlorobenzene, an even more difficult organic structure to analyze.

In 1945, Lonsdale was the first woman, along with microbiologist Marjory Stephenson, admitted as a fellow to the Royal Society. She was the first female professor at University College, London, the first woman named president of the International Union of Crystallography, and the first woman to hold the post of president of the British Association for the Advancement of Science. She accepted her achievements as a pioneering woman scientist with characteristic humility. In 1966, the "lonsdaleite," a...