Is this a fossil?

[Sarabande]

Found near John Day

 

 

[Lone Hunter]

That's really pretty and how unusual it's actually butterfly shaped!  I think that might be dendrites but wait for expert opinion.

[Ludwigia]

I agree with dendrites, a so-called pseudofossil.

[Rockwood]

I don't claim expertise at this, but my sense is that the pattern has more to do with the shape of the mineral crystals in the rock and the way the influenced the fracture.

[Lone Hunter]

The rock looks human shaped around the whatever to me.

[digit]

Yup. Dendrites are one of the most common pseudo-fossils. They can be quite pretty and deserve space in the display case despite being geologic and not biologic.

 

https://en.wikipedia.org/wiki/Dendrite_(crystal)

 

https://www.prehistoricoregon.com/learn/what-is-a-mineral/dendrite/

 

 

Cheers.

 

-Ken

[Rockwood]

Would dendrites form on ridges of a fracture, or am I seeing the contour wrong ? 

[digit]

Apparently, often emanating from fracture ridges.

 

Cheers.

 

-Ken

 

[supertramp]

Is it my impression or is the structure not only on the surface?

 

[Rockwood]

I see fracture ridges. No dendrites on them.

[digit]

The pattern suggests dendrites but this one looks to have continued to precipitate a lot of crystal growth mostly obscuring the fine dendritic patterns and possibly forming a more thickened 3-D structure.

 

I've only seen a few of these in person and am by no way an expert in these formations. @ynot

 

 

Cheers.

 

-Ken

[Rockwood]

23 minutes ago, digit said:

Apparently, often emanating from fracture ridges.

In a river like system, down grade. Not along the ridge. 

[digit]

Ah, I see your point now--slow at this time of the morning.

 

The dendrites appear to be emanating from the center of the plate and not from the edges where expected. Possibly, the counterpart to this plate had a crack in the middle from where these dendrites started. Only guessing.

 

 

Cheers.

 

-Ken

[Rockwood]

Maybe both crystal fracturing and dendritic overgrowth ? 

[JohnJ]

@Sarabande 

Can you show images using lower angled lighting that accentuates the surface texture?

[Scylla]

I think this is a fracture pattern, not dendrites. Very cool either way

[Denis Arcand]

Hi

 

I found a rock with a similar motif, I thought the pattern might be biological in nature, like mold or some other organism that got into a fracture in the rock before it split in two

 

Edited August 16, 2022 by Denis Arcand

[Scylla]

51 minutes ago, Denis Arcand said:

Hi

 

I found a rock with a similar motif, I thought the pattern might be biological in nature, like mold or some other organism that got into a fracture in the rock before it split in two

 

This is a classic example of dendrites

[supertramp]

On 8/16/2022 at 6:19 PM, JohnJ said:

@Sarabande 

Can you show images using lower angled lighting that accentuates the surface texture?

 

it would be desirable for Sarabande to give us some feedback on the questions we asked her, especially since the sample looks interesting.

For example, I would suggest providing pictures of the other sides of the sample (in addition to what JohnJ recommended); also, is there any information on the nature of the rock? I'm not even sure if it's volcanic (as I think) or sedimentary.

Come on Sarabande :-)