Name:
Collenia undosa Age: Precambrian Formation: Biwabik Formation Location: St. Louis County, Minnesota Size: Slab is 3.8'' X 7.5'' This specimen is not for sale Click here for similar specimens that are for sale
This is a very beautiful slab of a stromatolite from the Precambrian of Minnesota. Authorities believe that stromatolites were formed by masses of green or blue-green algae. This stromatolite has been estimated to be 2.1 to 2.7 billion years old! This thick slab has been highly polished on both sides. The pattern of mineral replacement is quite unusual, and the unique coloration makes for a striking display. This is a wonderful slab of this extremely old stromatolite from Minnesota.