Zircon mineral is the oldest one
on the Earth.
At least some detrital
ones from Westaern Australia are 4.4 billion years old.
Zircon is a silicate
mineral, and is a zirconium ore.
It is a hard mineral,
and very resistant to alteration.
It is found in
metamorphic and igneous rocks.
Thanks to its resistancy to chages it is used in dating rocks.