Terbium was discovered in 1843 by Swedish chemist Carl Gustaf Mosander, who detected it as an impurity in Yttrium-oxide, Y2O3, and named after the village Ytterby in Sweden.
Terbium is classified as a rare earth element.
Terbium is an inner transition metal (or lanthanide) that lies in period six of the periodic table, between gadolinium and dysprosium.
Terbium (chemical symbol Tb, atomic number 65) is a silvery-white rare earth metal.
Naturally occurring terbium is composed of one stable isotope, 159-Tb.
Terbium is never found in nature as the free element, but it is contained in many minerals.