A Possible Fossil?

[Darko]

Hi guys! 

I found this in Morava river...Idk what can this be,so any kind of help will be good! It doesn't look normal for some ordinary  rock so i hope that i've found a Fossil!

Thanks

[Rockwood]

Looks metamorphic to me. I don't think it's a fossil.

[JohnBrewer]

Looks geological to me too

[Ludwigia]

I'm also thinking that it's rather not a fossil, but I see what appears to be a recent clean break in the second photo bottom left. Could you show us a photo of that? Maybe that would help us a bit more to come to a decision.

[Miocene_Mason]

Looks like modern algal or lichen growths to me...

[Darko]

[Innocentx]

Pisolites.

 

https://en.wikipedia.org/wiki/Pisolite

[abyssunder]

Is the matrix brownish in color in daylight?
I have a similar one from Romania, river cobble, with these kind of inclusions visible all over the surface and in a brake. They are not only on the surface.
I think it's geological, but I don't know if it's igneous, metamorphic or sedimentary.

[KimTexan]

It is hard to tell from the pic if the rings are superficial, only on the surface, or if they go through the whole piece. 

I have several questions.

@Darko can you tell from the little break if the rings go deeper than the surface? If so that would rule out lichen or growth on the surface.

Also, does it change appearance significantly when wet? I’ve never seen a Petoskey Stone in person, but I don’t think they’re usually black, but they do have ring structures that go through the whole stone.

Do the rings have the same rock structure and hardness as the rest of the rock? 

Are the rings flush and smooth with the rock surface or do they protrude from the surface? I’m wondering if they’re a form of mineralization.

 

@WhodamanHD commented that they were lichen or algal growth on the rock. While there may be the occasional lichen that forms a ring that is not the typical lichen presentation. Lichen tend to form a mat or more solid rather than only a ring and you tend to see something in the middle of the ring. I think only rings without much in center may be ones that have died out.

pic from here http://www.nhm.ac.uk/natureplus/thread/8609?fromGateway=true

 

It does resemble pistolites.

 

http://sepmstrata.org/page.aspx?pageid=107

 

It does look like igneous rock, but if the rings formed during rock formation I’d expect vesicles rather than this appearance unless they were some type of inclusion, but with such thin margins I’d expect them to be destroyed by igneous rock formation process. So I tend to think the rings formed after the rock formed.

 

Sorry I’m all over the place on this one. I’m curious as to what it is and how it formed.

[KimTexan]

1 hour ago, abyssunder said:

Is the matrix brownish in color in daylight?
I have a similar one from Romania, river cobble, with these kind of inclusions visible all over the surface and in a brake. They are not only on the surface.
I think it's geological, but I don't know if it's igneous, metamorphic or sedimentary.

I’d be curious to see your sample.

[Darko]

50 minutes ago, KimTexan said:

It is hard to tell from the pic if the rings are superficial, only on the surface, or if they go through the whole piece. 

I have several questions.

@Darko can you tell from the little break if the rings go deeper than the surface? If so that would rule out lichen or growth on the surface.

Also, does it change appearance significantly when wet? I’ve never seen a Petoskey Stone in person, but I don’t think they’re usually black, but they do have ring structures that go through the whole stone.

Do the rings have the same rock structure and hardness as the rest of the rock? 

Are the rings flush and smooth with the rock surface or do they protrude from the surface? I’m wondering if they’re a form of mineralization.

 

@WhodamanHD commented that they were lichen or algal growth on the rock. While there may be the occasional lichen that forms a ring that is not the typical lichen presentation. Lichen tend to form a mat or more solid rather than only a ring and you tend to see something in the middle of the ring. I think only rings without much in center may be ones that have died out.

pic from here http://www.nhm.ac.uk/natureplus/thread/8609?fromGateway=true

 

It does resemble pistolites.

 

http://sepmstrata.org/page.aspx?pageid=107

 

It does look like igneous rock, but if the rings formed during rock formation I’d expect vesicles rather than this appearance unless they were some type of inclusion, but with such thin margins I’d expect them to be destroyed by igneous rock formation process. So I tend to think the rings formed after the rock formed.

 

Sorry I’m all over the place on this one. I’m curious as to what it is and how it formed.

Yeah, they go deeper than the surface,I can feel that under my finger..Yeah,it changes colour into white blue rings...And yes,they have Normal structure like whole stone,they are hard not worn

[ynot]

I think it is a Porphyritic rock, that has been stream tumbled.

 

Porphyry (geology) - (Wikipedia)
Porphyry is a textural term for an igneous rock consisting of large-grained crystals such as feldspar or quartz dispersed in a fine-grained silicate rich, generally aphanitic matrix or groundmass. The larger crystals are called phenocrysts. In its non-geologic, traditional use, the term porphyry refers to the purple-red form of this ...

Porphyritic rocks are formed when a column of rising magma is cooled in two stages. In the first stage, the magma is cooled slowly deep in the crust, creating the large crystal grains, with a diameter of 2 mm or more.

[KimTexan]

 

The stone has been worn away, but the rings did not wear away as much.

I am not a professional. I’m an armature wanna be. So I’m just trying to use the process of elimination here.

The differential wearing down of the material would tend to make me think it was a mineralization process of some sort that resulted in the rings, where the mineral is harder than the rock.

I suppose the rock could be any form, igneous, metamorphic or sedimentary. 

That is useful information, but we need someone else’s input. 

Abyssunder says he has a similar stone from Romania, but he is unsure of what his is as well, but thinks it’s geologic. 

It still reminds me a bit of a coral fossil, but you can’t see the other structures and some of the rings are so far from the others. The arrangement of the rings isn’t exactly consistent with the corals I’ve seen.

 

Here are are some pics of coral fossils I found on the web. I’m not sure what these would look like if they got worn down.

Can you see any traces of the coral structure on the rings?

[Darko]

I cannot tell for sure.I don't see any traces in the rings except the white stuff in it. 

[ynot]

44 minutes ago, KimTexan said:

some pics of coral fossils

Corals have a uniform size to their structures, this stone does not.

 

1 minute ago, Darko said:

I cannot tell for sure.I don't see any traces in the rings except the white stuff in it. 

I think You missed the post just before Kim Texan"s last post.

[supertramp]

if of magmatic origin, it reminds me, though not so typical, the so called orbicular texture https://www.google.it/search?q=orbicular+texture&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjVpZ7U2O_XAhVC1hoKHWLxDWIQ_AUICigB&biw=1517&bih=707

 

ciao

[Darko]

1 hour ago, supertramp said:

if of magmatic origin, it reminds me, though not so typical, the so called orbicular texture https://www.google.it/search?q=orbicular+texture&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjVpZ7U2O_XAhVC1hoKHWLxDWIQ_AUICigB&biw=1517&bih=707

 

ciao

Ćao.Thanks.

[abyssunder]

23 hours ago, KimTexan said:

I’d be curious to see your sample.

Unfortunately, I haven't get better than blurry images in this late our, but here they are:

 

[KimTexan]

Is that even the same rock? The first one kind of had the look of a short fat chicken leg. Pardon the analogy. Maybe it’s broken in half.

I see the blue now. When you said “white blue rings” I didn’t know what you were referring to. 

I think pisolite proposed by @Innocentx may be it. It’s curious though. This pic is from the link I posted on pisolites.

[Darko]

19 hours ago, KimTexan said:

Is that even the same rock? The first one kind of had the look of a short fat chicken leg. Pardon the analogy. Maybe it’s broken in half.

I see the blue now. When you said “white blue rings” I didn’t know what you were referring to. 

I think pisolite proposed by @Innocentx may be it. It’s curious though. This pic is from the link I posted on pisolites.

So finally, what is it?

[abyssunder]

Not fossils, in my opinion.

These are pisoids (with a maximum diameter around 5mm) encased in a pisolitic matrix formed to be a sphere polished on the surface, in my collection. As I remember correctly it's from Madagascar.

Your specimen doesn't resemble this. I'm leaning toward something like orbicular granite, as supertramp suggested.

 

 

[Innocentx]

@abyssunder  Where did this 3rd photo come from? It looks to be the mate of what @Darko found.

 

Can bacteria and algae be eliminated as playing a part in this formation?

[abyssunder]

The orbicular granite (third specimen from my previous post) is from Chile.

Yes, in the case if it's Orbicular granite .

[supertramp]

On 5/12/2017 at 1:01 AM, abyssunder said:

Unfortunately, I haven't get better than blurry images in this late our, but here they are:

 

 

Abyssunder, 

any chance it's an amygdaloidal (volcanic) and oxidated river tumbled stone? https://www.google.it/search?biw=1280&bih=918&tbm=isch&sa=1&ei=7-QnWqzKHIGZsAeE5oNw&q=amygdaloidal+rock&oq=amygdaloidal+rock&gs_l=psy-ab.3...11567.12374.0.12712.0.0.0.0.0.0.0.0..0.0....0...1c.1.64.psy-ab..0.0.0....0.ABNpUDG4xBc 

ciao

[abyssunder]

I was not convinced that it's a volcanic rock, but you're right, it really looks like the ones figured as amygdaloidal granite or basalt. Thanks for the link and suggestion.