This rock is an amazing, Precambrian aged fossil. The layered structures you see are stromatolites; the result of microscopic organisms producing alternating layers of sediment as they grow outward.
The source of the colors isn’t completely clear from the description, but I think they relate to some of the other nearby rocks in Minnesota, where this was found. Other ancient rocks in this area are the source of Minnesota’s major iron formations, and iron is probably a source of both the greenish and reddish/orange colors in this rock.
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