Léon G. A. de Marignac was a Swiss chemist born on August 3, 1817, in Geneva. He is best known for his work in the field of chemistry, particularly for his research on rare earth elements. De Marignac's studies contributed significantly to the understanding of these elements, which are crucial in various modern technologies. In 1885, de Marignac discovered the element ytterbium, which he isolated from the mineral ytterbite. His work laid the foundation for future research in the field of rare earth chemistry, influencing scientists like Marie Curie and Glenn T. Seaborg. De Marignac passed away on March 15, 1894.