In 1885, the discovery of neodymium was announced by splitting a relatively common earth called didymium into two new earths. The two new elements praseodymia (green didymia) and neodymia (new didymia), which are now known as praseodymium and neodymium, respectively.

Neodymium, a member of the lanthanide series of elements, is a silvery-white rare-earth metal. Commercial-grade neodymium is obtained from monazite sand, which is a mixture of phosphates of calcium, thorium, cerium, and is often 50% rare-earth by weight. Nearly 25% of naturally occurring neodymium is made up of radioactive ¹⁴⁴Nd. Its incredibly long half-life of 2,100,000,000,000,000 years has preserved its existence since the creation of the earth.

Neodymium is reactive to air and moisture. It tarnishes to form a light-blue oxide (Nd₃O₃), that flakes away to expose more metal for further oxidation. It has too little strength for structural use but has some value as an alloying agent and as a catalyst. Neodymium is used in the fabrication of artificial ruby for laser applications. In a pure form, it is useful in the glass industry as it produces the only bright-purple glass known. In a cruder state, it is used to eliminate the greenish tint in glass that has a high iron content. Neodymium is also used to make special glass that transmits the tanning rays of the sun but not the unwanted heat rays.