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Color in this red or pink series is annealed in geological conditions above temperatures of around 400°C.), one of the most refractory materials known.Other applications include use in refractories and foundry casting and a growing array of specialty applications as zirconia and zirconium chemicals, including in nuclear fuel rods, catalytic fuel converters and in water and air purification systems.As early as the middle of the 6th century, Securus Memor Felix, a professor of rhetoric, received the text in Rome, for his personal subscription at the end of Book I (or Book II in many manuscripts) records that he was working "from most corrupt exemplars".
In addition, the oxygen isotopic compositions of some of these zircons have been interpreted to indicate that more than 4.4 billion years ago there was already water on the surface of the Earth.
Zircons contain trace amounts of uranium and thorium (from 10 ppm up to 1 wt%) and can be dated using several modern analytical techniques.
Because zircons can survive geologic processes like erosion, transport, even high-grade metamorphism, they contain a rich and varied record of geological processes.
Connected to internal radiation damage, these processes partially disrupt the crystal structure and partly explain the highly variable properties of zircon.
As zircon becomes more and more modified by internal radiation damage, the density decreases, the crystal structure is compromised, and the color changes.