Unusual Form of Proterozoic Stromatolites with Rhodochrosite

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 prokaryotes (e.g, 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.

The unsual, rare and aesthetic characteristic of this example is a significant content of Rhodochrosite. Rhodochrosite (MnCO3, Manganese Carbonate - whose name means rose-colored) is a very attractive mineral with an absolutely one-of-a-kind, beautiful color that is a gemstone in crystal form, and otherwise used in various jewelry applications. Although it can be an ore of manganese, it is its ornamental and display specimen qualities that make it a very popular mineral..

Coming from the Chocolay Group in an area known as the Chocolay Hills located southeast of Ishpeming, Michigan, it dates to the Lower Proterozoic, some 2.2 to 2.4 Billion years old. This stromatolitic carbonate has been hand-polished to a mirror finish on one side which exhibits intricate banding and a spectrum of reddish-brown colors that are at once both vivid and awesome.