Ignacy Domeyko was born on July 31, 1802 in Niedźwiadka, Novogrodek district. After attending the Piarist College in Szczuczyn he studied at the Vilna University and got the M. Sc. degree in 1822. As member of the illegal Philomat Society was interned till 1829. In 1831 as participant of anti-Russian insurrection had to escape to Prussia, from where moved to Saxony and France. In the years 1832-1838 Domeyko was studying exact and geosciences at Sorbonne and École des Mines. Invited by the Government of Chile was teaching physico-chemical and geo-sciences in the Coquimbo College in La Serena in the years 1838-1846, carrying out large-scale geological and ethnographic field studies as well as chemical-mineralogical investigations. In the years 1846-1884 Domeyko was very active as academic teacher and in the period 1867-1883 as rector of the Chile University in Santiago, continuing research works and reforming local education system. His many-sided activity contributed significantly to economic and educational progress of Chile. In the final stage of his life (1884-1888) Domeyko, as already world-wide known scientist, could visit his homeland and other European countries, as well as Holy Land, but on the way back felt ill and on January 23, 1889 died in Santiago admired and venerated by Chileans as their apostle of science and education. The present paper deals with essential Domeyko's achievements in geosciences. Already during his stay in Paris the results of his observations on sinking of the area of East Prussia in historic times were published and Domeyko has prepared the geographic atlas of the territory of the native Polish-Lithuanian Commonwealth but only its part could be printed. In Chile, apart from didactic activity, accented by edition of handbooks on mineralogy and assaying, Domeyko was carrying out large-scale geological, mining and mineralogical investigations of Andes showing predilection to chemical analyses of collected materials. As follows from the inspection of archival materials, he is the author of at least 160 analyses of various, often chemically very complicated, minerals (including meteorites) and about 60 analyses of waters. This resulted in the discovery of several new minerals which were announced in renowned European periodicals. One of them - copper arsenide - was named by W. Haidinger domeykite. Besides, several Andean fossils sent by Domeyko to France were by A. d'Orbigny and other French palaeontolo- gists named after their discoverer. Following several minor papers on regional geology, including detailed studies of volcanic phenomena, he published in 1878 in Polish a monograph on Chilean Cordilleras and ore deposits, comparing some their fragments with similar horizons in the Polish Carpathians. These and other problems treated by Domeyko in numerous publications are discussed in the present paper. Domeyko's achievements were highly appreciated by several European and American scientific societies and universities by conferring him memberships and honorary doctorates. Moreover, due to his exceptional personality and spirituality, expressed in deeply Christian virtues realized in private and social life, Domeyko is a candidate for beatification. Geoscientists of Poland, Lithuania, Chile, Belorussia, France and other countries are celebrating 200th anniversary of his birth, paying homage to this eminent citizen of the world.