Reidite
The high-pressure form of zircon, a lasting fingerprint of asteroid impacts.
Key facts
- Formula
- ZrSiO4
- Family
- High-pressure minerals
- Crystal system
- Tetragonal
What it is
Reidite has the same composition as zircon but a denser, scheelite-type structure. It was first made in 1969 by the Australian scientist Alan Reid in high-pressure experiments, and is named after him. Natural reidite was first reported in 2001 from impact ejecta, and it is now known from about ten impact structures on Earth and from a lunar meteorite.
Where it is found
It forms thin lamellae or patches within zircon grains in rocks shocked by impacts, at sites such as Chesapeake Bay, Ries, Rochechouart, Haughton and Woodleigh. Because zircon is tough and resists weathering, reidite can survive for hundreds of millions of years.
How it is recognised
It is identified by Raman spectroscopy or electron backscatter diffraction within zircon grains, where it forms crossing lamellae.
Did you know?
Reidite has been found in a lunar meteorite as well as in Earth's impact structures.
It forms at pressures of roughly 20 to 30 gigapascals, far beyond those of ordinary geology.