René Just Haüy (French pronunciation: ?[a?i]) FRS MWS FRSE (28 February 1743 – 3 June 1822) was a French priest and mineralogist, commonly styled the Abbé Haüy after he was made an honorary canon of Notre Dame.
Due to his innovative work on crystal structure and his four-volume Traité de Minéralogie (1801),
he is often referred to as the "Father of Modern Crystallography".
During the French revolution he also helped to establish the metric system.