Tellurium

Tellurium is a p-type semiconductor for electronics use.   It also improves the machineability of copper and stainless steel, decreases corrosion of sulfuric acid on lead and improves its strength and hardness.   Tellurium adds chill control to cast iron.   It also is used in blasting caps and ceramics.   Bismuth telluride is used in thermoelectric devices. ^{Lide 4-29}

Tellurium was discovered by the Austrian minerologist, Franz Joseph Muller von Reichenstein, in 1782 and isolated by the German chemist, Martin Heinrich Klaproth in 1798.   Tellurium can be found free, but it is usually associated with gold in calaverite and with other metals.   It is prepared commercially by recovery from anode muds in electrolytic refining of blister copper. ^{Lide 4-29}