Lower Proterozoic Banded Iron from Michigan
"The Rusting of the Earth"

This banded iron testament to the rusting of the earth in the Lower Proterozoic is classic and dense, with high content of magnetite (Fe3O4), a natural magnet. The pictures speak adequately to its inherent beauty. The color changes dramatically with angle of incident light from black to silver (compare the pictures). Note the various size streaks of maroon-colored sediment. Whether the sediment was of bioorganic origin (stromatolite) is indeterminable, but likely.

The specimen has been hand-polished to a glassine finish on one side with fine carbide and diamond abrasive, a very labor-intensive job. The pictures comparing front and back reveal the value of this form of polishing.