Zircons

Zircon (ZrSiO4) is a ubiquitous mineral in the earth’s crust. Because the material is chemically inert and hard, it is very resilient to weathering processes and can persist for a long time in a large variety of sedimentary, igneous, and metamorphic rocks. When zircon crystals are formed from a melt, conditions can vary over time which affects the zircon growth. Such changes in conditions lead to zonation in the zircon (zones of zircon which contain different amounts of trace elements, for instance). Similar to the growth rings in trees, these zones contain chronological information about the geological formation of the zircons.