Unique Stromatolites from Minnesota

With Hydrothermal Rhodochrosite Intrusion

Polished Stromatolites

Geological Time: Early Proterozoic. ~ 1.8 Billion Years Old

Size: Stromatolite fossil is 73 mm by 47 mm by 13 mm thick (maximum)

Fossil Site: Tommald Formation, Merritt #2 Mine, Cayuga North Range, Crow Wing County Minnesota

Code: DS18034

Price: $45.00

Stromatolites from MinnesotaFossil Description: This banded iron is metasediment (sediment that has undergone metamorphism) and has a high content of magnetite (Fe3O4), resulting in the midnight black and red coloration. Minute crystalline forms of other mineral-based compounds are also present; Whether the sediment was of bioorganic origin (stromatolite) is indeterminable, but likely. The rich pink sections are the result of intrusion by Rhodochrosite (Manganese Carbonate) and Rhodonite (Manganese Iron Magnesium Calcium Silicate). This material is the result of hydrothermal activity which is typically accompanied by various extremophilic organisms, making for a most unique duality of biogenic sources. Since the manganese minerals are intrusive, they are obviously younger, although by how much is not known.

The specimen has been hand-polished to a glassine finish on one side with fine carbide and diamond abrasive, a very labor-intensive job. It comes from a 30 year old deposit which is no longer available. The coloration seen here is most striking.

Stromatolites have persisted to the modern day in such places as Shark Bay, Australia where they continue their billions of years old lifestyle. While this piece would make a fine present for any natural history buff, anyone who appreciates art would also be glad to get thus wonderful specimen as a gift.

Fossils for Sale

click stromatolites pictures to enlarge

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