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How to tell a stromatolite?


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I have been unsuccessful in getting information about this on the general internet (the All-Knowing Google failed me, AGAIN! :blink: ).

How in the world can you tell if a rock that you have in hand is a stromatolite as opposed to just a rock with striations- like agate or something? Especially if the stromatolite has had a section cut and polished? 

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I don't think there is a quick and easy way to distinguish these things. :unsure: 

I think you need to study Fossil Stromatolite Anatomy.    HELPFUL LINK

Familiarize yourself with the look of fossil stromatolites

You need to search Google Scholar, and add "PDF" to your search terms.  ;) 

LINK 1

 

 

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What Tim said. It might be impossible to tell with a small fragment or slice if all you see are flat layers, as a number of processes can create layers (like basic sedimentation), but if you see some of the characteristic shapes, like the mounds etc. in those links, then there's a better chance that you've got a stromatolite.

Where you picked the piece up might also have some bearing. Is it an 'orphaned' piece (no location known)?

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3 hours ago, Fossildude19 said:

I don't think there is a quick and easy way to distinguish these things. :unsure: 

I think you need to study Fossil Stromatolite Anatomy.    HELPFUL LINK

Familiarize yourself with the look of fossil stromatolites

You need to search Google Scholar, and add "PDF" to your search terms.  ;) 

LINK 1

 

 

THANK you, Fossildude19! :thumbsu:

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2 hours ago, Wrangellian said:

What Tim said. It might be impossible to tell with a small fragment or slice if all you see are flat layers, as a number of processes can create layers (like basic sedimentation), but if you see some of the characteristic shapes, like the mounds etc. in those links, then there's a better chance that you've got a stromatolite.

Where you picked the piece up might also have some bearing. Is it an 'orphaned' piece (no location known)?

There are several different pieces available for purchase, and I’m tempted but leery. They are from different specific locations ranging from Brazil to Minnesota and Ontario.

 

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20 hours ago, Moozillion said:

There are several different pieces available for purchase, and I’m tempted but leery. They are from different specific locations ranging from Brazil to Minnesota and Ontario.

 

The stuff from Minnesota ("Mary Ellen Jasper") is definitely stromatolite. I've got a few pieces of this stuff myself. Any North American fossil collection that spans geologic time needs a piece of that!

Not sure about Brazil but you frequently see stuff from Bolivia. It definitely looks like stromatolite but it might not be Precambrian as many of the dealers have assumed. I understand it is only Cretaceous in age.

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2 hours ago, Wrangellian said:

The stuff from Minnesota ("Mary Ellen Jasper") is definitely stromatolite. I've got a few pieces of this stuff myself. Any North American fossil collection that spans geologic time needs a piece of that!

Not sure about Brazil but you frequently see stuff from Bolivia. It definitely looks like stromatolite but it might not be Precambrian as many of the dealers have assumed. I understand it is only Cretaceous in age.

Thanks, Wrangellian! :rolleyes:

I'll post photos of the stromatolites offered to see what people think. 

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This is offered as Mary Ellen Stromatolite from the Mary Ellen mine, Mesabi Range in Minnesota. It is 4 x 6 inches, 5/8 inch thick and weighs 1 lb 10 oz. Based on internet photos I've seen, this seems legit. What are your thoughts? @Wrangellian and anyone else! :rolleyes:

 

 

fullsizeoutput_c4f.jpeg

fullsizeoutput_c50.jpeg

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Looks right to me. 

It is different to my Collenia undosa from the Mary Ellen mine :

Collenia2.thumb.jpg.aaa8976965c40a7f1ddd89a5c7e45360.jpg

But I have seen other pieces like yours, still has that blend of red jasper and haematite, so I think it's okay. 

But let's see what others think..........................

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That’s a Mary Ellen Jasper, MN stromatolite.

As these are also MEJ from MN

I’ve picked up another piece that’s close to looking like the one you posted but I don’t have a picture of that right now, could post it after work.

 

Picture didn’t come through correctly, it’s tilted side ways, if someone could fix it thank you.

 

D9CA8323-966C-404D-B800-D9A3A34D550D.jpeg

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Mooz....

I know who’s selling that item, I like it too.

as you can see, if it’s a nice size with nice pattern or color of MEJ I’ll buy it.

 

I still have another 7 hours to work, & I’ll give you time to buy it before I do :whistle:
tic toc  :default_rofl:
 

As for the Bolivia piece he’s selling is legit & good price.

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1 hour ago, Abyss said:

Mooz....

I know who’s selling that item, I like it too.

as you can see, if it’s a nice size with nice pattern or color of MEJ I’ll buy it.

 

I still have another 7 hours to work, & I’ll give you time to buy it before I do :whistle:
tic toc  :default_rofl:
 

As for the Bolivia piece he’s selling is legit & good price.

Thanks for the warning- I think I'll go ahead and get it! :wub:

Yes, that Bolivian piece is GORGEOUS but just a bit pricey for me. I've already gone beyond my stated budget, but gosh dang it, I'd kick myself if I didn't get it. 

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2 hours ago, Abyss said:

Mooz....

I know who’s selling that item, I like it too.

as you can see, if it’s a nice size with nice pattern or color of MEJ I’ll buy it.

 

I still have another 7 hours to work, & I’ll give you time to buy it before I do :whistle:
tic toc  :default_rofl:
 

As for the Bolivia piece he’s selling is legit & good price.

...aaaaand he JUST posted a gorgeous stromatolite from very early Cambrian border Morocco! (but I still went with that red one!:P)

 

I recently completed a course on Behavioral Addictions as required by my job. The lecture included Gambling Addiction, Eating Addiction, Hoarding etc. but they OBVIOUSLY omitted FOSSIL Addiction!!!! :D

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20 hours ago, Moozillion said:

This is offered as Mary Ellen Stromatolite from the Mary Ellen mine, Mesabi Range in Minnesota. It is 4 x 6 inches, 5/8 inch thick and weighs 1 lb 10 oz. Based on internet photos I've seen, this seems legit. What are your thoughts? @Wrangellian and anyone else! :rolleyes:

 

 

fullsizeoutput_c4f.jpeg

fullsizeoutput_c50.jpeg

Interesting piece - lots going on there, different colors. There is some interesting variation in the Minnesota material...

I recently bought a chunk of Mary Ellen that looks to be brecciated stromatolite. Stands to reason that shallow-water colonies could get broken up by waves and buried. I just can't figure out where those hematite(?) grains came from that surround the stromatolite bits!:

 

MaryEllen1.jpg

MaryEllen2.jpg

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7 hours ago, Abyss said:

That’s a Mary Ellen Jasper, MN stromatolite.

As these are also MEJ from MN

I’ve picked up another piece that’s close to looking like the one you posted but I don’t have a picture of that right now, could post it after work.

 

Picture didn’t come through correctly, it’s tilted side ways, if someone could fix it thank you.

 

D9CA8323-966C-404D-B800-D9A3A34D550D.jpeg

Some nice pieces there, particularly the two on the right. The green stuff I understand is harder to come by and I still don't have a decent example of it, like yours.

On the other hand maybe I should just attend one of those Behavioural Addiction courses that Mooz speaks of! (Like a lot of us here, no doubt)

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Here’s a recent picture of my MEJ MN stromatolites.

The upper left is one of the newer pieces close to OP type, the two bottom pieces right under green piece are not polished- though are wet for picture.

 

 

3677B3D7-2846-48AD-B2FC-6432288077FD.jpeg

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1 hour ago, Wrangellian said:

Interesting piece - lots going on there, different colors. There is some interesting variation in the Minnesota material...

I recently bought a chunk of Mary Ellen that looks to be brecciated stromatolite. Stands to reason that shallow-water colonies could get broken up by waves and buried. I just can't figure out where those hematite(?) grains came from that surround the stromatolite bits!:

 

MaryEllen1.jpg

MaryEllen2.jpg


 

Northern MN is heavily rich in Iron, hence the Nickname “ Iron Range “

 

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3 hours ago, Abyss said:

Here’s a recent picture of my MEJ MN stromatolites.

The upper left is one of the newer pieces close to OP type, the two bottom pieces right under green piece are not polished- though are wet for picture.

 

 

3677B3D7-2846-48AD-B2FC-6432288077FD.jpeg

Beautiful!

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22 hours ago, Abyss said:

Northern MN is heavily rich in Iron, hence the Nickname “ Iron Range “

 

That's what I gather. But what is happening - did bits of iron weather off the land into the sea in little grains, and get deposited around the stromatolites? Or is it recrystallized after the fact?

I'm familiar with Banded Iron, but these are little grains, evenly sorted, apparently. Maybe it's more of an oolite phenomenon, but they look metallic.

 

MaryEllen-det.jpg

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2 minutes ago, Wrangellian said:

That's what I gather. But what is happening - did bits of iron weather off the land into the sea in little grains, and get deposited around the stromatolites? Or is it recrystallized after the fact?

I'm familiar with Banded Iron, but these are little grains, evenly sorted, apparently.

The bacteria that form stromatolites gave off oxygen as a by-product, of course. The water at this time was rich in iron. The oxygen reacted with the ferrous iron to make haematite. . 

(i read up on this when i got my bit.):D

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1 minute ago, Tidgy's Dad said:

The bacteria that form stromatolites gave off oxygen as a by-product, of course. The water at this time was rich in iron. The oxygen reacted with the ferrous iron to make haematite. . 

(i read up on this when i got my bit.):D

Yes, I've read about that too - that explains the Banded Iron deposition, which is normally flat layers... I'm just wondering how it got formed into even-sized grains in my specimen.

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11 minutes ago, Wrangellian said:

Yes, I've read about that too - that explains the Banded Iron deposition, which is normally flat layers... I'm just wondering how it got formed into even-sized grains in my specimen.

Maybe centred around other microbes within the stromatolites? 

See https://www.researchgate.net/publication/222646774_Iron-oxidizing_microbial_ecosystems_thrived_in_late_Paleoproterozoic_redox-stratified_oceans

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