Pyrite Replaced Archaean Stromatolites in Siderite

Stromatolites - Thyssagetes sp microbials

Hand Polished

Geological Time: Archaean, ~ 2.7 ro 2.75 Billion Years Old

Size: Stromatolite fossil is 190 mm by 90 mm (maximum)

Fossil Site: Helen Iron Formation, MacLeod Shaft Mine, Wawa, Ontario, Canada

Code: DS17062

Price: $265.00

Description: This specimen comes from a shaft mine in Ontario that has been closed for many years. It is the first instance of stromatolite reported from siderite. The dark laminae are outlined by coarse secondary pyrite, pyrroholite, and magnetite. The oganisms are of the genus Thyssagetes, and represent the oldest examples of the Thyssagtaceae. It has been proposed that the depositional environment was an ephemeral volcanic basin. The presence of the microbes generating stromatolitic features were most likely living at temperatures below 110 degrees and possibly even lower that 73 degrees. The destruction of some laminae and the presence of all fours phases of iron minerals (siderite, pyrite, pyrroholite, and magnetite) are indicative of substantial modification of the original stomatolitic carbonate. The occurrence of stromatolites in siderite are not only unique for the Archaen but for all of geologic time. This is the second and LAST example I have to offer.

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.

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click stromatolites pictures to enlarge

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