Baddeleyite
Zirconium oxide, a tiny but powerful clock for dating Martian, lunar and asteroid basalts.
Key facts
- Formula
- ZrO2
- Family
- Oxides
- Crystal system
- Monoclinic
What it is
Baddeleyite is zirconium oxide. Like zircon, it takes in uranium but almost no lead when it crystallises, so it can be dated by the uranium–lead method. It crystallises in basaltic rocks too poor in silica for zircon.
Where it is found
It occurs in shergottites, eucrites, angrites, lunar basalts and some mesosiderites. Dating baddeleyite in shergottites has given ages of a few hundred million years for their crystallisation on Mars.
How it is recognised
It forms microscopic brown grains, found by their brightness in electron images.
Did you know?
Baddeleyite is named after Joseph Baddeley, who brought the first samples from Sri Lanka.
Shock can turn zircon into tiny grains of baddeleyite, a clue to high temperatures in impacts.