Hafnium is a silvery metal element with the symbolHf occurring in zircon and used in nuclear reactors in the control rods and also used for light-bulb filaments. It was named in 1923 by the Dutch physicist Dirk Coster and Hungarian chemist Georg von Hevesy after the city of Copenhagen, where the element was discovered (Hafnia is Latin for Copenhagen). Research Hafnium
Zircon was a codename for a British spy satellite originally intended to be launched 1988. The revelation of the existence of the Zircon project (which had been concealed by the government) by the journalist Duncan Campbell, and the government's subsequent efforts to suppress a programme about it on BBC television, caused much controversy in 1987, not least for the bumbling way the security forces raided Campbell's office but failed to find his notes about the project which were concealed in computer files with anonymous names. Its intended function was to intercept radio and other signals from the USSR, Europe, and the Middle East and transmit them to the Government Communications Headquarters (GCHQ) in Cheltenham, England. Research Zircon
Zirconium is a lustrous, greyish-white, strong, ductile, metallic element, with the symbolZr. It occurs in nature as the mineral zircon (zirconium silicate), from which it is obtained commercially. It is used in some ceramics, alloys for wire and filaments, steel manufacture, and nuclear reactors, where its low neutron absorption is advantageous. Research Zirconium
Hyacinth or jacinth is a red variety of zircon, sometimes used as a gem stone. Its crystals, when distinct, have the form of a four-sided prism, terminated by four rhombic planes, which stand on the lateral edges. Its prevailing colour is a red, more or less tinged with yellow or brown. The name hyacinth is also given to varieties of the garnet or cinnamon stone, the sapphire, and topaz. Research Hyacinth
Jargon (also known as Jargoon or Jacynth or Matara Diamond) is a colourless, yellowish or smoky coloured variety of zircon found in Sri Lanka. Research Jargon
Scapolite has the formulae (Na,Ca,K)4A13(Al,Si)3Si6O24(Cl,SO4,CO3) and a relative hardness of 6. It shows fluorescence. Occurs in the crystalline schists, gneisses, and often is probably derived from the alteration of plagioclase feldspars. Also occurs in crystalline limestones formed by metamorphic contact or igneous intrusion. Associated with diopside, amphibole, garnet, apatite, and zircon. Research Scapolite
Zircon (zirconiumsilicate) has the formulae ZrSiO4 and a relative hardness of 8. It is a common accessory mineral found in all types of igneous rocks. When transparent it's used as a gemstone.
Zircons contain abundant radioactive isotopes of uranium and so are useful for uranium-lead dating to determine the ages of rocks. Research Zircon
The Probert Encyclopaedia was designed, edited and programed by
Matt and Leela Probert
Abbreviations
Research Hafnium
