Zirconium was discovered as zirconium oxide in 1789 by Klaproth who worked with the mineral zircon (ZrSiO4), zirconium silicate in the form of semiprecious gemstones from Ceylon. Such zircon gems derive their name from the Arabic zargun (gold color) and Klaproth named the element zirconium. J. J. Berzelius first produced the metal in 1824 in impure form by the reduction of K2ZrF6 with potassium. The first ductile metal of good purity was made by the reduction of resublimed zirconium tetrachloride with high-purity sodium, first by Lely and Hamburger in 1914 in Germany and later in the early 1920's by Cooper and Hunter in the USA. In 1925, van Arkel and de Boer applied their iodide decomposition process to make very pure zirconium.