Jasper Knob, Ishpeming
The Jasper Knob banded iron formation, or BIF, is approximately 2 billion years ago. It is a result of changes in the oxygen content of the surronding ocean. During times of high oxygen, iron was oxidized (2+ to 3+), and it precipitated out to form a black, and during times of low oxygen, iron was not oxidized and did not precipitate out, forming a red layers. The red layers are iron stained chert (SiO2), and the white layers are either Magenetie (Fe2O4) or Hematite (FeO3).
Banded Iron Formation at Jasper Knob.
A view of Ishpeming from Jasper Knob