gems, zircon, Sri Lanka, Ceylon

Landmark chemical investigation of zircon in which Klaproth analyzed specimens from Ceylon (Sri Lanka). Using yellowish-green and reddish zircons, he decomposed the mineral by fusion with alkali and subsequent treatment with acids. His experiments demonstrated that zircon contained a previously unrecognized earth distinct from silica, alumina, lime, and magnesia. Klaproth named this constituent Zirkonerde (zircon earth; zirconia), thereby identifying the oxide of the element later called zirconium. The investigation was particularly important because earlier analyses, including Wiegleb’s 1787 study of Ceylon zircon, had failed to recognize zirconia as a distinct substance. Klaproth’s work established the chemical individuality of zircon and represents the discovery of zirconium in the form of its oxide.