Selenium is a non metal, sometimes considered a metalloid, rarely occurring in its elemental state on earth but mainly in the earth’s crust in sulfide ores. Industrially, Selenium is obtained as a byproduct of the refining sulfide ores but is usually produced in an ore, not as a pure substance. It is commonly used in glassmaking and pigments. It also has some use as a semi-conductor and electronics due to its ability to conduct a current. Selenium was discovered by Jöns Jakob Berzelius and Johan Gottlieb Gahn. Both scientists owned a factory producing Sulphuric acid from which a red precipitate was created. When burned the red substance gave off a strange smell which they first thought was Tellurium. It was not until 1818 when Alexander Marcet analysed the red precipitate identifying the element Selenium. It is located in Group 16 and it has a melting point of 221°c and a boiling point of 685°c being a solid at room temperature.
Light causes it to conduct electricity more easily. It is used in photoelectric cells, TV cameras, xerography machines and as a semiconductor in solar batteries and rectifiers. Also colors glass red.
Obtained from lead, copper and nickel refining. Conducts electricity when struck by light.