René Just Haüy (February 28, 1743 - June 3, 1822), French mineralogist, commonly styled the Abbé Haüy, from being an honorary canon of Notre Dame, was born at St Just, in the départment of Oise.

His parents were in a humble rank of life, and were only enabled by the kindness of friends to sond their son to the college of Navarre and afterwards to that of Lemoine. Becoming one of the teachers at the latter, he began to devote hie leisure hours to the study of botany; hut an accident directed his attention to another field in natural history. Happening to let fall a specimen of calcareous spar belonging to a friend, he was led by examination of the fragments to make experiments which resulted in the statement of the geometrical law of crystallization associated with his name.

The value of this discovery, the mathematical theory of which is given by Haüy in his Traité de minéralogie, was immediately recognized, and when communicated to the Academy, it secured for its author a place in that society. Haüy's name is also known for the observations he made in pyroelectricity.

When the Revolution broke out, he was thrown into prison, and his life was even in danger, when he was saved by the intercession of Étienne Geoffroy Saint-Hilaire. In 1802, under Napoleon, he became professor of mineralogy at the museum of natural history, but after 1814 he was deprived of his appointments by the government of the Restoration. His latter days were consequently clouded by poverty, but the courage and high moral qualities which had helped him forward in his youth did not desert him in his old age; and he lived cheerful and respected till his death at Paris.

The following are his principal works:

• Essai d'une théorie sur la structure des crystaux (1784)
• Exposition raisonne de la théorie de l'électricité et du magnétisme, d'après les principes d'Aepinus (1787)
• De la structure considérée comme caractére distinctif des minéraux (1793)
• Exposition abrége de la théorie de la structure des cristaux (1793)
• Extrait d'un traité élmentaire de minéralogie (1797)
• Traité de minéralogie (5 vols, 1801)
• Traité élémentaire de physique (2 vols 1803, 1806)
• Tableau comparatif des résultats de la cristallographie, et de l'analyse chimique relativement a la classification des minéraux (1809)
• Traité des pierres précieuses (1817)
• Traité de cristallographie (2 vols, 1822)

He also contributed papers, of which 100 are enumerated in the Royal Society's catalogue, to various scientific journals, especially the Journal de physique and the Annals du Museum d'Histoire Naturelle.