Whose work first identified cerium as a new element, now the most abundant rare earth element?

Cerium was identified in 1803 from the mineral cerite, with key work by Jöns Jacob Berzelius and Wilhelm Hisinger, while Martin Klaproth independently reached the same conclusion in Germany. The element was named after Ceres, the asteroid discovered in the same year. Cerium became one of the first recognized rare earth elements and is now known as the most abundant of them. Its discovery is a classic example of how astronomy and chemistry influenced each other at the time. Cerium is used today in catalytic converters and alloys.