Precambrian Stromatolites Section from Wisconsin with Greenish Cast

Description: Precambrian stromatolite is the oldest of all fossils, and with much labor (cutting and polishing), it is most beautiful. The banding that commonly appears in stromatolite is a record of the growth patterns of colonies of microorganisms, principally photosynthetic cyanobacteria. The colors that are often expressed are the result of the interaction of biological and sedimentary processes, together with subsequent chemistry and mineral exchange. While polished stromatolite is often quite attractive, seldom are such traces of rich green color seen. This unique fossil is also very ancient, dating back to the boundary of the Archean and the Proterozoic in Precambrian time. This was a time on Earth when the environment was still hostile to life as we know it today. It was a time when bacteria reigned supreme, and the cyanobacteria that produced their energy through photosynthesis were ubiquitous and were busily oxygenating the Earth's atmosphere. This was near the peak of stromatolite formations on Earth. This stromatolite is the oldest microfossil of Wisconsin and occurs below the banded iron formations (see my other listing for an example).