They are formed by crystallization from a metamorphic rock and they are 4.4 billion years old so they or scientists study because they are 4.4 billion years old
Zircon helps scientists to study the early earth because it is the oldest thing in the earth.
It is the result of the crystallization from metamorphic rock. So, by studying the zircon stone scientist would know about the climate, temperatures and other things of the early earth.
EXPLANATION:
Zircon stone is believed to be 4.4 billion years old hence the oldest thing present on the earth toady.
By studying the zircon stone it can be predicted the events that could have been occurred 4 billion years ago.
