Holmium

Holmium, chemical element, symbol Ho; for physical constants see Periodic Table. Holmium was discovered spectroscopically in 1878 by M. Delafontaine and J.L. Soret. It occurs in gadolinite and other rare-earth minerals and is commercially obtained from monazite. Elemental holmium is prepared by reducing its anhydrous chloride with calcium metal. Holmium is a silvery, soft, reactive metal. It has interesting magnetic properties. Holmium belongs to the series of elements known as the rare-earth metals. Ion-exchange and solvent extraction techniques have led to much easier isolation of these elements. Holmium and its compounds are used in carbon-arc lighting applications, special types of glass, enamels, and refractory materials.