Could this be a type of coral?

[Sandfossil]

I am going through a collection of rocks I acquired cleaning and trying to identify. I know how important location is but in this case I honestly have no idea. This one reminded me of a coral but thought I should ask the experts.

Thank you for looking and your time.

 

[Ludwigia]

Yes, this could very well be an agatized coral in my opinion. It would definitely look nice cut and polished and perhaps it could then be identified if the corallites, septa and columella can be seen well.

[abyssunder]

Pictures are blurry...

[Sandfossil]

2 hours ago, Ludwigia said:

Yes, this could very well be an achatized coral in my opinion. It would definitely look nice cut and polished and perhaps it could then be identified if the corralites, septa and columnella can be seen well.

Thank you for responding. I will try to get a cut when it warms up a bit. My saw is in my shop, unfortunately there's no heat and my saw is about 50 years old. So I treat her gingerly if you know what I mean. But I will post a picture as soon as I cut it. Should I do the cut horozontally?

[Sandfossil]

28 minutes ago, abyssunder said:

Pictures are blurry...

I used my friends phone to take the pictures as his is brand new and I had people comment on pictures I posted previously with my phone being blurry. So I did try to do better. I will try again maybe take them outside. Thanks for the comment.

[digit]

It does indeed look curious. I'm thinking the alignment of the white spots are not really regular enough to seem like a colonial coral. I'm thinking the white centers surrounded by red rings seems more like mineral inclusions. The rock does look highly silicified and would probably look quite interesting if you could slice it open and see a nice clean surface. I'm not convinced that it is coral and any orientation would probably reveal detail (or the lack thereof). Looking forward to seeing inside when things warm up enough to spin up the saw.

 

 

Cheers.

 

-Ken

[Sandfossil]

I am now attempting pictures from my sons phone until I get to cut it. Thank you all for having patience with me.

[Ludwigia]

2 hours ago, Sandfossil said:

Should I do the cut horozontally?

Depends on what horizon you're talking about...I'm also now tending to think that this is not coral.

[abyssunder]

It looks close to "ocean jasper".

Edited February 4, 2022 by abyssunder

[oyo]

+1 for something mineral. It doesn't look like a coral to me.

[Sandfossil]

  I appreciate everyones opinion. I do believe The Fossil Forum is invaluable to a beginner like me. For me to learn I have to be able to understand the "Why it's not such and such."  I do try to do some research so I started my search on the spherulites that are found on the ocean jasper like posted above. It lead me to some articles that led to other articles. The last one was interesting but may confuse me so I hope someone with a higher education could put it in layman's terms. And I hope I am not breaking any rules as in posting links. 

https://pubmed.ncbi.nlm.nih.gov/32590171/

Again I Thank you all.

Cyndi

 

 

[digit]

The first sentence of the abstract here is a good overview of this paper:

"Spherulites are radial distributions of acicular crystals, common in biogenic, geologic, and synthetic systems, yet exactly how spherulitic crystals nucleate and grow is still poorly understood."

 

Though it contains a higher density of big 25-cent words than the average person would consider tossing into conversation, the key point here is that spherical crystals (spherulites) with the crystals oriented from a point in the center (radial distribution) are common in nature. They can be biogeneic--the result of life forms, corals for example or they can be the result of purely geologic processes with no involvement of any life form. They can even be produced synthetically (through some man-made industrial process).

 

Here's an interesting (hopefully) aside on "biogenic crystals":

 

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

 

Corals precipitate calcium carbonate (CaCO₃) from sea water in a crystalline form known as aragonite to build the limestone skeleton that supports the soft polyp body. Most mollusks likewise produce aragonitic shells called valves (as in bivalves). Some mollusks and most enchinoderms produce a calcium carbonate exoskeleton but the CaCO₃ crystals are laid down in a different arrangement of crystals called called calcite. These mollusk shells (oysters, scallops and a few others) and sea urchin/sand dollar tests (the exoskeletons that fossilize) are referred to as calcitic and since calcite is more impervious to decomposition urchin tests and oyster and scallop shells are often preserved when other mollusk shells have dissolved leaving only hollow shell casts in the fossil record. A good way of thinking about this is that graphite and diamond are both crystal structures composed purely of the element carbon. In graphite the carbon atoms form hexagonal rings (honeycomb shape) that slide easily past each other forming the soft material that makes up pencil "lead" while the tetrahedral network of carbon atoms in diamond are much stronger forming a substance noted for its hardness.

 

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

 

Corals and other marine animals are capable of producing tiny calcium carbonate crystals for their exoskeleton but most of these are pretty microscopic. Crustacean shells are much more like our bones in that the small calcium carbonate crystals are formed within a network of protein fibers. This gives them strength but just a bit of flexibility. Coral skeletons are composed of countless numbers of these microscopic crystals arranged into a pattern specific to the shape of the coral polyp itself. Corals are a colonial animal comprised of individuals (polyps) that are joined together by both living tissue at the surface and the communal limestone skeleton below. Though the biogenic spherulites (CaCO₃ crystals produced by the coral animal itself) are spherical and radial in nature, they are microscopic and pretty much invisible to the naked eye. The confusion between geologically produced spherulites that may continue to grow to sizes easily visible without magnification and coral polyps is that the polyps are also radial in nature:

 

https://link.springer.com/chapter/10.1007/978-81-322-3658-0_10

 

 

Fossilized colonial corals tend to have ridged lines (costae) interconnecting the regularly arranged calices (the circular skeleton that surrounds the individual polyps). None of these features are visible in your specimen which is what is leading our members who are familiar with fossilized corals to lean toward this being a geologic specimen with randomly arranged (and quite colorful) spherulites distributed throughout the rock. Hope this proves helpful in answering the questions you turned up with the paper you found. This mass of information above will hopefully fill in some knowledge gaps and possibly provide new leads for further questions. As always, feel free to as questions. Information presented here may help you in the present and others coming across this discussion in the future.

 

 

Cheers.

 

-Ken

 

 

[DPS Ammonite]

Looks like orbicular or poppy jasper. Compare to Morgan Hill Jasper from California.

 

https://gilroydispatch.com/poppy-jasper-the-rock-behind-the-film-festival/

[Sandfossil]

1 hour ago, digit said:

The first sentence of the abstract here is a good overview of this paper:

"Spherulites are radial distributions of acicular crystals, common in biogenic, geologic, and synthetic systems, yet exactly how spherulitic crystals nucleate and grow is still poorly understood."

 

Though it contains a higher density of big 25-cent words than the average person would consider tossing into conversation, the key point here is that spherical crystals (spherulites) with the crystals oriented from a point in the center (radial distribution) are common in nature. They can be biogeneic--the result of life forms, corals for example or they can be the result of purely geologic processes with no involvement of any life form. They can even be produced synthetically (through some man-made industrial process).

 

Here's an interesting (hopefully) aside on "biogenic crystals":

 

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

 

Corals precipitate calcium carbonate (CaCO₃) from sea water in a crystalline form known as aragonite to build the limestone skeleton that supports the soft polyp body. Most mollusks likewise produce aragonitic shells called valves (as in bivalves). Some mollusks and most enchinoderms produce a calcium carbonate exoskeleton but the CaCO₃ crystals are laid down in a different arrangement of crystals called called calcite. These mollusk shells (oysters, scallops and a few others) and sea urchin/sand dollar tests (the exoskeletons that fossilize) are referred to as calcitic and since calcite is more impervious to decomposition urchin tests and oyster and scallop shells are often preserved when other mollusk shells have dissolved leaving only hollow shell casts in the fossil record. A good way of thinking about this is that graphite and diamond are both crystal structures composed purely of the element carbon. In graphite the carbon atoms form hexagonal rings (honeycomb shape) that slide easily past each other forming the soft material that makes up pencil "lead" while the tetrahedral network of carbon atoms in diamond are much stronger forming a substance noted for its hardness.

 

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

 

Corals and other marine animals are capable of producing tiny calcium carbonate crystals for their exoskeleton but most of these are pretty microscopic. Crustacean shells are much more like our bones in that the small calcium carbonate crystals are formed within a network of protein fibers. This gives them strength but just a bit of flexibility. Coral skeletons are composed of countless numbers of these microscopic crystals arranged into a pattern specific to the shape of the coral polyp itself. Corals are a colonial animal comprised of individuals (polyps) that are joined together by both living tissue at the surface and the communal limestone skeleton below. Though the biogenic spherulites (CaCO₃ crystals produced by the coral animal itself) are spherical and radial in nature, they are microscopic and pretty much invisible to the naked eye. The confusion between geologically produced spherulites that may continue to grow to sizes easily visible without magnification and coral polyps is that the polyps are also radial in nature:

 

https://link.springer.com/chapter/10.1007/978-81-322-3658-0_10

 

 

Fossilized colonial corals tend to have ridged lines (costae) interconnecting the regularly arranged calices (the circular skeleton that surrounds the individual polyps). None of these features are visible in your specimen which is what is leading our members who are familiar with fossilized corals to lean toward this being a geologic specimen with randomly arranged (and quite colorful) spherulites distributed throughout the rock. Hope this proves helpful in answering the questions you turned up with the paper you found. This mass of information above will hopefully fill in some knowledge gaps and possibly provide new leads for further questions. As always, feel free to as questions. Information presented here may help you in the present and others coming across this discussion in the future.

 

 

Cheers.

 

Ken

Thank you so much for the wonderful explanation and taking the time to educate me. Where do I pay my tuition? LOL.

So my understanding is that corals have a crystalline exoskeleton structure but there will be more definitive rigid structures but spherulites in rock tend to be more blurred and not as rigid. 

I read about tubular spherulites  thinking my specimen might be that but I think it isn't because the tubes are random and not in colums tightly together. I do still plan on cutting it open. 

These are valuable lessons. 

I bet I have heard a 100 NO's but it only encourages me to dig a little deeper. Ignorant I may be, but willing and wanting to learn, that's me.

Thanks Again.

Cyndi

[Sandfossil]

18 minutes ago, DPS Ammonite said:

Looks like orbicular or poppy jasper. Compare to Morgan Hill Jasper from California.

 

https://gilroydispatch.com/poppy-jasper-the-rock-behind-the-film-festival/

I think you are correct. Not only did I find out its NOT coral but it IS Poppy Jasper. What an amazing place here. Thank you for taking the time to help me.

[digit]

3 hours ago, Sandfossil said:

Where do I pay my tuition? LOL.

Hang around here for a while, absorb some knowledge and pay it forward when you spot a newer member asking questions that you've now learned the answer to.

 

3 hours ago, Sandfossil said:

So my understanding is that corals have a crystalline exoskeleton structure but there will be more definitive rigid structures but spherulites in rock tend to be more blurred and not as rigid. 

Search the forum here (or the wider inter-webber-net) for images of "fossil coral" and you'll see lots of examples. You'll notice more structure (finer details) in these fossil coral skeletons. Your circular crystal formations are more "blurred" as they seem to be spherical crystals growing in an orderly pattern dictated by chemical processes that allow atoms to link-up into crystal lattices. Usually, life forms end up making more complicated patterns as they tend to be the relics of functional parts of animal and plant structures necessary for living. Here's a great example of a purely geologic (chemical) process creating structures that mimic organic life that often confuse and amuse folks:

 

 

3 hours ago, Sandfossil said:

These are valuable lessons. 

I bet I have heard a 100 NO's but it only encourages me to dig a little deeper. Ignorant I may be, but willing and wanting to learn, that's me.

There is no shame in being "ignorant". I'm ignorant (often by choice) on whole ranges of topics of which I have no interest. Willingness to learn is what separates someone hoping to fill a knowledge vacuum from someone who knows very little but insists they are correct (and that they know more than all the experts). It is no secret that social media is rife with this kind of ignorance--here we much prefer the eager uninformed looking to learn.

 

 

Cheers.

 

-Ken

[Sandfossil]

@digit Found this in some of the papers of the man whose rock collection I have. Thought how appropriate for me and maybe some others. Might change the name from rocks to fossils.