ThomasT
has rocks in the head
Member since June 2022
Posts: 616
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Post by ThomasT on Jul 9, 2024 14:35:09 GMT -5
tribeunited I have read and studied a lot but I'm not the resident paleontologist...
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Post by tribeunited on Jul 9, 2024 14:37:28 GMT -5
tribeunited I have read and studied a lot but I'm not the resident paleontologist... Gotcha. Maybe someone will splain things to me.  |
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Post by cabby on Jul 9, 2024 14:54:04 GMT -5
tribeunited I have read and studied a lot but I'm not the resident paleontologist... Gotcha. Maybe someone will splain things to me. Stromatolites still exist. They are just big mats of “blue-green algae” (Cyanobacteria, not algae). You think they are a jasper because they were replaced with silica, like petrified wood. I know this is a generic, simplified way of saying a rather complex topic (not all are Cyanobacteria, not all have organic material, etc)… but it’s basically petrified blue-green algae blooms. |
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Post by tribeunited on Jul 9, 2024 15:02:41 GMT -5
I see! Thank you, my understanding is growing a bit. I didn't have such deep or knowledgeable thoughts on silica replacement to be honest cabby . I think they are a jasper because they exist only in slabs for me. I see a slab, and if I can't see though it when held to light I think - oh must be a jasper! Unless it clinks or feels funky - then I jump to rhyolite.... When that fails, I come here and have everyone else think for me help me. |
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Post by cabby on Jul 9, 2024 15:06:28 GMT -5
I see! Thank you, my understanding is growing a bit. I didn't have such deep or knowledgeable thoughts on silica replacement to be honest cabby . I think they are a jasper because they exist only in slabs for me. I see a slab, and if I can't see though it when held to light I think - oh must be a jasper! Unless it clinks or feels funky - then I jump to rhyolite.... When that fails, I come here and have everyone else think for me help me. Well, lucky you, jasper is a very very common replacement, so it *is* jasper 😆 it’s only really the “what is it that pattern” that is different… of course, it’s not always jasper for stroms but if you have jasper with that label, it’s jasper. |
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Post by liveoak on Jul 9, 2024 15:24:52 GMT -5
I’ve been looking at this rock for years wondering what it is. The only thing I can come up with is stromatolite. I have no idea where it’s from. What do you folks think?    That is WAY cool !
I'd be tempted to cut off a slab or two & keep the rest as a specimen.
Thanks for showing it.
Patty
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Post by cabby on Jul 9, 2024 16:09:30 GMT -5
Starguy just realized that your rock looks incredibly similar to an off cut I found…   if it’s anything like the one I have, I would definitely slab it up!
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ThomasT
has rocks in the head
Member since June 2022
Posts: 616
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Post by ThomasT on Jul 9, 2024 16:38:29 GMT -5
It appears to me a lot of "cold water" agates possibly began as stromatolites too...
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Post by cabby on Jul 9, 2024 17:08:17 GMT -5
It appears to me a lot of "cold water" agates possibly began as stromatolites too... I, personally, have no experience with it, but from videos I’ve watched it seems like agatized stromatoporoid (sponges) are fairly common in the same places you can pick up Michigan cold water agates. They are frequently both shown in the same videos. |
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RWA3006
Cave Dweller 
Member since March 2009
Posts: 4,625 
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Post by RWA3006 on Jul 9, 2024 18:55:11 GMT -5
I’ve been looking at this rock for years wondering what it is. The only thing I can come up with is stromatolite. I have no idea where it’s from. What do you folks think? Yes, it is stromatolite in one of its many varieties. I've seen a lot of identical specimens in the field of southern Utah. It often appears in large mats that look very much like algae in a creek. I found a bank of it about 8' wide and 30' long that looks very different from the blob shaped ones I find in Wyoming. |
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RWA3006
Cave Dweller
Member since March 2009
Posts: 4,625
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Post by RWA3006 on Jul 9, 2024 19:02:28 GMT -5
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Post by vegasjames on Jul 9, 2024 19:09:56 GMT -5
Also found in Mexico.
It is believed that Earth's oxygen was produced from stromatolites.
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Post by cabby on Jul 9, 2024 19:17:15 GMT -5
Cyanobacteria oxygenating the earth caused a MASSIVE extinction at least once. I believe that BIF is one of the trace type stroms from excessive oxygenation
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dshanpnw
fully equipped rock polisher
Member since December 2020
Posts: 1,157
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Post by dshanpnw on Jul 9, 2024 19:21:41 GMT -5
Thanks for all the info on Stromatolites. I don't have any of them yet. Super interesting thread RWA3006.
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gemfeller
Cave Dweller
Member since June 2011
Posts: 4,059
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Post by gemfeller on Jul 9, 2024 20:29:16 GMT -5
Cyanobacteria oxygenating the earth caused a MASSIVE extinction at least once. I believe that BIF is one of the trace type stroms from excessive oxygenation Can you document that extinction event? I've researched it a little and can't find it. It seems a bit strange to me that the creation of oxygen, which led to a huge explosion in life on Earth, also caused an extinction of that life. Not arguing, just curious. |
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RWA3006
Cave Dweller
Member since March 2009
Posts: 4,625
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Post by RWA3006 on Jul 9, 2024 20:47:24 GMT -5
Cyanobacteria oxygenating the earth caused a MASSIVE extinction at least once. I believe that BIF is one of the trace type stroms from excessive oxygenation Can you document that extinction event? I've researched it a little and can't find it. It seems a bit strange to me that the creation of oxygen, which led to a huge explosion in life on Earth, also caused an extinction of that life. Not arguing, just curious. |
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Post by liveoak on Jul 10, 2024 6:15:16 GMT -5
They are also found in the Bahamas. There is a very interesting video on the link below, explaining what they are made off & how they helped create life on the planet !
bahamas-marine-ecocentre.org/stromatolites/Patty |
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Post by tribeunited on Jul 10, 2024 13:41:17 GMT -5
I don't know what this is exactly, but I think it's a stromolite. I asked some expert types in the ID section first to make sure.   |
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Post by liveoak on Jul 10, 2024 15:35:45 GMT -5
I'm going to go out on a limb here- but maybe that's Mary Ellen ?
Patty
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Post by tribeunited on Jul 11, 2024 13:20:30 GMT -5
liveoak - That was the discussion we had yesterday. I believe it is a banded iron formation mined at the Mary Ellen mine in Bilwibik MN. Whether it is considered Mary Ellen or not was up for debate, as it is metallic.
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