Selenium Selenium Selenium is a chemical element with symbol Se and atomic number 34. It is a nonmetal (more rarely considered a metalloid) with properties that are intermediate between the elements above and below in the periodic table, sulfur and tellurium, and also has similarities to arsenic. It rarely occurs in its elemental state or as pure ore compounds in the Earth's crust. Selenium (from Ancient Greek (selḗnē) "Moon") was discovered in 1817 by Jöns Jacob Berzelius, who noted the similarity of the new element to the previously discovered tellurium (named for the Earth). Selenium is found in , where it
Antimony gangue minerals. Antimony can be isolated from the crude antimony sulfide by reduction with scrap iron: The sulfide is converted to an oxide; the product is then roasted, sometimes for the purpose of vaporizing the volatile antimony(III) oxide, which is recovered. This material is often used directly for the main applications, impurities being arsenic and sulfide. Antimony is isolated from the oxide by a carbothermal reduction: The lower-grade ores are reduced in blast furnaces while the higher-grade ores are reduced in reverberatory furnaces. Antimony has consistently been ranked high in European and US risk lists concerning criticality of the element