Ignacy Domeyko (also spelt Domejko; Belarusian: Ігнат Іпалітавіч Дамейка) (b. July 31, 1802 in Мядзьведка, Belarus - January 23, 1889 in Santiago de Chile) was a geologist and mineralogist.

He studied at the Vilnius University and the Ecole des Mines in Paris. Ignacy was a close friend of the writer Adam Mickiewicz. After being involved in the November Uprising in 1831, he chose to emigrate to France instead of facing Russian reprisals. In 1838 he left for Chile, where he lived until May 22 1884, when he left for Europe.

He was a professor of a mining college at Coquimbo and later (1867-1883) president of the University of Santiago de Chile .

He greatly developed studies in mineralogy and mining techniques, researched several new minerals, and was also a meteorologist and ethnographer.