Question

The picture shows a type of rock called a banded iron formation. The rock contains high levels of iron oxides minerals, which form only when iron at Earth's surface combines with oxygen. Approximately how old would Earth's oldest banded iron formations be? 3 billion years old 4.6 billion years old 5 billion years old 65 million years old

Answer 1

These rocks are very old, BIF date to as old as 3 billion years old, but most are aged at around 2.5 billion and some are as "young" as 1.8 billion. 

ANSWER:  the Earth's oldest banded iron formation is 3 billion years old.