Lanthanum was discovered in 1839 by Carl G. Mosander. He was searching for impurities he believed existed in samples of cerium. He took finely powdered cerium nitrate and added nitric acid. Some of the cerium nitrate powder dissolved in the acid indicating a new earth might be present. The new oxide was more basic than ceria (cerium oxide) and, unlike ceria, dissolved in the acid. Mosander separated the solution from the precipitate and obtained a pale brick-coloured oxide of the new rare earth. The name comes from the Greek word lanthano meaning to be hidden.