Show us your stromatolites

[MarcoSr]

5 hours ago, nala said:

Stromatolites of the Upper Precambrian in the Adrar of Mauritania (western. Sahara).

 

 

 

Really nice specimens.

 

I’ve posted a couple of pieces in this thread that the authors of Leis, Stinchcomb, Mckee, 2015, Stromatolites Ancient, Beautiful, and Earth-Altering call dubiostromatolites (look like stromatolites, but for various reasons their biogenicity is questioned).  The authors show the two figures below.  In figure 6-28 the authors say "they could be biogenic” and in Figure 6-29 they say “are not (almost certainly) stroms”.

 

 

 

 

 

Marco Sr.

[Wrangellian]

19 hours ago, MarcoSr said:

 

Yes and the wrinkles have more or less regular troughs and crests with amplitudes in the range of 0.3–3 mm with intercrest distances of 1–5 mm which match the descriptions in the paper.  I'm pretty certain now, after reading the paper and looking at pictures, that the slab shows evidence of a microbial mat.

 

 

Where pieces come from is always a question, especially when the sellers don't collect the piece themselves.  The piece should look nice polished.  I can hand polish the cut face, but I may want to get the rest of the rough surface lightly polished (not freeform as I still want texture) to show detail there also.

 

Marco Sr.

That sounds much smaller than I would gauge from your photo and measurements (15.2" long?) on your piece... that would make the ripples roughly 1/2" wide, no?

I wouldn't polish the rough outer surface of the Larsonite piece, but it's your piece. I like a natural 'crust' on a piece along with the cut/polished surface.

21 hours ago, nala said:

Few samples,

Stromatolite – Acaciella australica Howchin, 1914. Precambrian, Bitter Springs Group. Gillen Member Fitzroy Crossing, Ross River District. Northern Territory Australia

Stromatolite. Conophytum basalticum Walter, 1972. Precambrian, Antrim Basalt formation.Top Spring near 'Wave Hill' Pastoral Station. Northern Territory Australia

Stromatolite. Late Pleistocene. Marion Lake, Stenhouse Bay area. South Australia.

Stromatolite from Assas (around Montpellier) dating from 300 million years ago France

Stromatolites of the Upper Precambrian in the Adrar of Mauritania (western. Sahara).

Very nice. I'm particularly envious of your Australian Precambrian pieces.

[Yoda]

I have one of these Stroms. It was given to me as a gift. 
My research leads me to believe that they are not true Stromatolites and they are not biological in origin. 
 

 

[MarcoSr]

5 hours ago, Wrangellian said:

That sounds much smaller than I would gauge from your photo and measurements (15.2" long?) on your piece... that would make the ripples roughly 1/2" wide, no?

 

The largest wrinkle width is 3/8 of an inch (only a couple that size) and most wrinkles are 1/4 inch or narrower.  The wrinkles are all flat on top with the wrinkle tops (crests) all in the same plane which matches the paper.  So there really isn't a crest somewhere in the wrinkle top, the entire wrinkle top is the crest.  If you read the paper the 1mm to 5mm dimension is basically the distance between the wrinkle tops which is really only slightly larger than the trough width.  I can measure the wrinkle heights at the edge of the piece (where you can clearly see that the wrinkle tops are flat and the same height)  because they are distinctive, like flat clay ribbons on a flat base.  All the wrinkle tops (crests) that I can see on the edge of the piece are roughly 2mm in height which fall in the .3mm to 3mm range for Kinneyia-type wrinkle structures.  So everything matches the paper, the dimensions, the pattern, and the pattern orientations.

 

EDIT:  This picture of two wrinkles at the edge of the piece should show what I'm trying to explain.

 

 

 

 

 

Marco Sr.

Edited June 5, 2021 by MarcoSr
Added picture, changed ripple to wrinkle

[Wrangellian]

OK. The pic is maybe a little deceptive from this end without a scale but I'll take your word for all that. I don't mean to be argumentative. To settle any remaining doubts I might have I would like to know what is the smaller end of the size range for regular (wave) ripples, to see if there is any overlap, and I don't think ripples necessarily have crests, as they may have somewhat settled before being buried by successive layers. But don't worry about that, I'm not about to suggest you remove the piece from the topic!

 

23 hours ago, Yoda said:

I have one of these Stroms. It was given to me as a gift. 
My research leads me to believe that they are not true Stromatolites and they are not biological in origin.

Right... I've got a couple of those and that is what I gather about them too. Doesn't hurt to include non-biogenic 'impostors' in this topic also, in the interest of education.

Edited June 6, 2021 by Wrangellian

[Tidgy's Dad]

There are lots of stromatolites in Morocco, but the above are not them. 

Here's mine.

One of my very first posts on the forum was about this , back in 1850 or so. 

It seems to be a desert formation, like a desert rose and is not a fossil. Still very interesting and possibly as old as the Cretaceous. 

[Yoda]

Another South American Stromatolite 

 

 

[MarcoSr]

3 hours ago, Wrangellian said:

OK. The pic is maybe a little deceptive from this end without a scale but I'll take your word for all that. I don't mean to be argumentative.  I'm not about to suggest you remove the piece from the topic!

 

 

I'm removing myself from this thread.  Those comments are unacceptable to me.  First to suggest that I would lie about the dimensions and then to suggest I should remove my posts because you don't agree.

 

Marco Sr.

 

[Notidanodon]

9 hours ago, MarcoSr said:

 

I'm removing myself from this thread.  Those comments are unacceptable to me.  First to suggest that I would lie about the dimensions and then to suggest I should remove my posts because you don't agree.

 

Marco Sr.

 

hi Marco you have made several great contributions to this thread and it would be a shame to back out of a very informative topic.  
meanings can become muddled through text as desired sentiments can become misconstrued without visible emotions, I don’t think @Wrangellian meant to offend you, by calling the pic deceptive, I’m not sure that was the meaning he intended, I think he meant that it is harder to judge without the scale, and I think he was being genuine when saying you shouldn’t remove pieces from the topic and it just came across slightly differently to you  

If you don’t feel it is correct to continue then there is no pressure on you to recommence, but it would be a shame for the community for you to stop sharing your wonderful knowledge and personality  

[Wrangellian]

21 hours ago, MarcoSr said:

I'm removing myself from this thread.  Those comments are unacceptable to me.  First to suggest that I would lie about the dimensions and then to suggest I should remove my posts because you don't agree.

Marco Sr.

Will is right, you misread my comment completely! Maybe my language can be a little dense at times, but I meant that MY interpretation of your photo and the data is imperfect (not your fault, and you didn't lie), that I was willing to accept your conclusions about it being microbial, and that I would NOT suggest you remove it from the topic! Even if it turns out not to be microbial, it can be helpful to show things that can be mistaken for such. Please don't drop out, I appreciate your contributions.

Edited June 7, 2021 by Wrangellian

[Tidgy's Dad]

On 6/6/2021 at 10:54 AM, MarcoSr said:

 

I'm removing myself from this thread.  Those comments are unacceptable to me.  First to suggest that I would lie about the dimensions and then to suggest I should remove my posts because you don't agree.

 

Marco Sr.

 

Yup, I'm out too. 

[FranzBernhard]

On 6/6/2021 at 12:54 PM, MarcoSr said:

On 6/6/2021 at 9:17 AM, Wrangellian said:

OK. The pic is maybe a little deceptive from this end without a scale but I'll take your word for all that. I don't mean to be argumentative.  I'm not about to suggest you remove the piece from the topic!

 

 

I'm removing myself from this thread.  Those comments are unacceptable to me.  First to suggest that I would lie about the dimensions and then to suggest I should remove my posts because you don't agree.

 

I am clearly a non-English speaker, because I don´t understand a single word of this! 

Franz Bernhard

[Wrangellian]

OMG, what is going on? I'm seriously doubting my ability to communicate now and think I should distance myself from the forum altogether. Too much of a minefield. Otherwise I don't know what to do to get out of this mess.

Edited June 8, 2021 by Wrangellian

[Notidanodon]

On 6/7/2021 at 1:45 PM, Tidgy's Dad said:

Yup, I'm out too. 

Adam why? You’re not helping what was an almost resolved situation, it was just a misunderstanding  

[FranzBernhard]

1 hour ago, will stevenson said:

it was just a misunderstanding

Indeed! That´s all! Hence my comment !

 

@MarcoSr, @Wrangellian, @Tidgy's Dad

 

Franz Bernhard