It ranks about 58th in abundance among the elements in crustal rock and occurs in extremely small quantities as a white oxide known as terbia in such minerals as gadolinite. Terbium was discovered in 1843 by a Swedish chemist, Carl Gustav Mosander. It can be produced by reducing the anhydrous chloride or fluoride with calcium metal in a tantalum crucible.
Terbium oxide is used as an activator for green phosphors used in color television tubes.
Sodium terbium borate is used in solid-state devices. Bayer Corporation is a research-based company with major businesses in health care and life sciences, and chemicals.