Possible fossile in a breccia?

[CornelDumitru]

Hello to you all!

This is my first post here.

Collecting rocks and minerals is a hobby of mine, also lapping/cabbing/faceting.

I picked up this stone in Romania, Harghita county. It seemed interesting so I lapped 4 sides (last 4 photos attached).

Then I polished all of it. Then I took some photos, 5 of them attached (there is a strip of laser printed paper, with 1 mm grid, included in each one of them).

This stone has 70 mm in the longest dimension; 2.77 specific gravity; was 330 grams before lapping. 

Most of material should be carbonates; it dissolves in vinegar with gas bubble production.

The stone is, I guess, a breccia. A polymictic breccia. A multi-generation breccia: some clasts are breccia-in-breccia.

Many clasts look sedimentary. The variety of clasts is puzzling, at least to me. If the photos attached are not puzzling, I have more to show.

Hydrothermal alteration could be involved. Ancient sea bed could be involved (Transylvania was a sea, once). Rock melt and re-crystallization could be involved, or meteorite bombardment.

I have no idea.

The main feature of interest here is the 1-mm diameter "wheel" with "spokes", & co.

Is it a fossil? Have you ever seen something like this?

 

Edited July 16, 2021 by CornelDumitru

[digit]

37 minutes ago, CornelDumitru said:

The main feature of interest here is the 1-mm diameter "wheel" with "spokes", & co.

Is it a fossil? Have you ever seen something like this?

 

Looks like a cast of a single corallite. The darker circle with the radiating lines toward the center would have been the original calcium carbonate skeleton.

 

Internet image searches for "corallite" should provide examples (modern and fossil).

 

 

Cheers.

 

-Ken

[CornelDumitru]

Thanks, Moderator!

 

BINGO!

 

So I picked the stone 2 weeks ago, I found this forum last evening (it's 3 a.m. now here...), worked 2 hours to put together the posting, and got my answer in 30 minutes.

Positive!

 

Edited July 16, 2021 by CornelDumitru

[FranzBernhard]

6 hours ago, CornelDumitru said:

The stone is, I guess, a breccia. A polymictic breccia. A multi-generation breccia: some clasts are breccia-in-breccia.

Nice polymict carbonate breccia. 

 

5 hours ago, digit said:

Looks like a cast of a single corallite.

I think, I can see another one. And some shell fragments?

 

6 hours ago, CornelDumitru said:

Rock melt and re-crystallization could be involved, or meteorite bombardment.

No, no obvious signs for such processes.

 

Franz Bernhard

[Ludwigia]

8 hours ago, CornelDumitru said:

 

Is it a fossil? Have you ever seen something like this?

 

 

2 hours ago, FranzBernhard said:

 

I think, I can see another one.

 

 

I think he means this:

 

[TqB]

It (the original specimen) looks like a textbook scleractinian coral, with the first two cycles of septa 6 + 6. 

[CornelDumitru]

6 hours ago, FranzBernhard said:

I think, I can see another one. 

 

4 hours ago, Ludwigia said:

I think he means this:

 

That particular area looks different now (after cabbing the stone). More coral fossils!

[CornelDumitru]

4 hours ago, TqB said:

It (the original specimen) looks like a textbook scleractinian coral, with the first two cycles of septa 6 + 6. 

 

And this one is from the same textbook page, I guess.

 

[JamieLynn]

what a fantastic rock! 

[CornelDumitru]

18 minutes ago, JamieLynn said:

what a fantastic rock! 

Yes it is, thank you!

Also seen in contrasting led light / LWUV light.

[FranzBernhard]

Thanks for showing us more pics!

 

I am getting an upper Cretaceous ("Gosau") vibe for your breccia. Have you found patterns like that in your breccia:

Transverse and longitudinal section of radiolitid rudists. Plenty of rudists in Romania .

Franz Bernhard

[CornelDumitru]

1 hour ago, FranzBernhard said:

Have you found patterns like that in your breccia:

Hah! I was ready to go 5 days before you asked the question!

I had no idea what it was that made me take photos.

Do they qualify?

Now I have to go read about radiolitid rudists.

 

[FranzBernhard]

9 minutes ago, CornelDumitru said:

Do they qualify?

Not as radiolitid rudist cellular outer shell of its lower valve .

Seriously, I have not seen such a pattern in rudists. And I don´t know what could it be...

Franz Bernhard

[abyssunder]

Welcome from Romania! 

When I've seen this picture I thought I see something like a "chrysanthemum stone" as inclusion in your breccia.

 

[CornelDumitru]

On 7/17/2021 at 6:12 PM, FranzBernhard said:

Have you found patterns like that in your breccia:

There is this specimen.

[FranzBernhard]

Now we are getting close, some of them look really like radiolitid fragments.

Here are two links to plates on my homepage, various sectioned radiolitids for comparison:

Radiolitid 1

Radiolitid 2

 

Franz Bernhard

[CornelDumitru]

4 hours ago, FranzBernhard said:

Now we are getting close

 

The scale is off by half an order of magnitude at least. Other than that, compared with your formidable plates, the 3 mm square-ish patch present on this breccia could be a rudist cellular outer shell fossil fragment, by no excessive stretch of imagination.

I see linear parallel rows of polygonal cells.

I am happy with that.

 

Edited July 19, 2021 by CornelDumitru

[abyssunder]

I think almost all of the fossils there are rudist fragments in different sections, probably from the Senonian reefs of Romania.

Here are some pictures of rudists (not from Romania) which may have pattern similar to the ones from your breccia.

Edited July 20, 2021 by abyssunder

[CornelDumitru]

There is one more feature here that caught my eye.

The risk of becoming a nuisance to this forum notwithstanding, I will ask if this is a possible (gastropod?) fossil.

 

[FranzBernhard]

9 hours ago, CornelDumitru said:

I will ask if this is a possible (gastropod?) fossil.

Not gastropod, but could very well be a fragment of a rudist shell.

Franz Bernhard

[Sjfriend]

Very cool piece! A fossilized fossil

 

Welcome to the forum!