Whose discovery first identified selenium as a new element with properties like sulfur and tellurium?

Jöns Jacob Berzelius discovered selenium in 1817 during an investigation of material from a sulfuric acid plant. At first he thought the substance might be tellurium, but analysis showed it was a different element. He named it selenium, from Selene, the Moon, because of its relationship to tellurium, which had been named after Earth. Selenium turned out to have chemical properties between sulfur and tellurium, making it a useful example of periodic behavior before the periodic table existed. Berzelius was one of the great systematizers of chemistry.