Crystallography365

Blogging a crystal structure a day in 2014

Index

Contributed by

Helen Maynard-Casely

How old? – The crystal structure of Zircon

What does it look like?

Image generated by the VESTA (Visualisation for Electronic and STructual analysis) software http://jp-minerals.org/vesta/en/

What is it?

How do we know how old our planet is? Well it's largely thanks to this mineral, Zircon. Made up of Zirconium atoms (green) with silicate (SiO4) tetrahedra (blue with the red oxygen atoms in the corners), when this mineral forms it often traps trace amounts of Uranium and Thorium. These radioactive elements can be used in radiometric dating to determine how old that specimen is, which is especially useful as zircon is a pretty tough mineral and can survive a number of geological processes intact. Zircons from Jack Hills, in Western Australia, have been dated to be 4.4 billion years old, making them the oldest known rocks to have formed on our planet.

Where did the structure come from?

The structure of Zircon was fist determined by Bink et al. in 1926, and is #1011265 in the Crystallography Open Database.

Tags: mineral   dating   zircon   oldest rock