Zirconium hydride an ore, usually a zirconium silicate, such as zircon. Zirconium is extracted from zirconium ore by removing the oxygen and silica. This process, known as the Kroll process, was first applied to titanium. The Kroll process results in an alloy containing hafnium. The hafnium and other impurities are removed in a subsequent step. Zirconium hydride is created by combining refined zirconium with hydrogen. Like titanium, solid zirconium dissolves hydrogen quite readily. The density of zirconium hydride varies based the hydrogen and ranges between 5.56 and 6.52 g cm. Even in the narrow range of concentrations which make up zirconium hydride,
Cubic zirconia of diamond. Cubic zirconia is relatively hard, 8–8.5 on the Mohs scale— slightly harder than most semi-precious natural gems. Its refractive index is high at 2.15–2.18 (compared to 2.42 for diamonds) and its luster is adamantine. Its dispersion is very high at 0.058–0.066, exceeding that of diamond (0.044). Cubic zirconia has no cleavage and exhibits a conchoidal fracture. Because of its high hardness, it is generally considered brittle. Under shortwave UV cubic zirconia typically fluoresces a yellow, greenish yellow or "beige". Under longwave UV the effect is greatly diminished, with a whitish glow sometimes being seen. Colored stones may show