Is this a coprolite?

[Zesus]

 

Hello all,

 

Thanks for letting me post my inquiry. I was wondering if any of you could give your input on a large "rock" that I found in my yard. I live in Menlo Park, California which is about a mile north of Stanford University in the San Francisco Bay Area.  Please excuse my ignorance when it comes to the fossil world. I have zero knowledge in this area, but i must say that after only a few days of investigating websites and forums I find it quite fascinating. And also a massive black hole lol.. I have spent all of my free time looking into the topic the past couple days. so many hours!!  (not complaining, its been awesome!)

 

Anyways I will attach pictures below. The only reason I think it is a coprolite is because of the many other "rocks" that I have also found on the property, about 20 or so, that fit many pictures I have seen on the internet. But this one doesn't really look like any of the others and is quite large, at least double the size of the others.  

 

At first glance I thought it to be chunk of a wood round, as i have found petrified wood on the property, at least what I believe to be petrified wood. When I picked it up I noticed that it was very heavy, probably 30+ pounds, so definitely not fresh wood as this is way to dense to be so. Gave it a knock and its rock hard. On most of the outside there are small flakes of something shiny, some metallicy and some more clear, some faintly yellow/green.. I dont know if its crystal or something else but they seem to be thin pieces of something, some layered on top of each other. What struck me at first was the green that was viewable in some spots. This is the reason I picked it up in the first place to investigate further. 

 

The one green spot is mostly white now actually. After I noticed the green I had a piece of sand paper handy and I gave a quick rub on the white part to see if more green was under it and there was. However a day later the green has gone back to white. Not sure if thats from oxygen exposure or possibly the abrasiveness of the sandpaper causing scratches which turned white with time.  

 

The outraged just looks really really old is the best way I can sum it up. There was a small section that was slightly sticks out and cracked a bit so I knew it would come of easy. Gave it a wack with a chisel and it popped off.  I will attach pictures of that as well.  I have scraped at a couple sections, trying to see what was inside, and it seems to be green and brown in most. Parts have a serpentine look to them, which was my second guess after wood.  But the rock just seemed to be to "living" if that makes sense.  There are vertical and horizontal cracks throughout some with some sort of white lining in them. I really want to crack it open as I think it might be quite beautiful, based on the weight and density. 

 

Anyways I could go on but I will just post some photos and hopefully you can help me out a bit, because at the end of the day I really have no clue and don't pretend to. Also, another question I have.. Is it possible to have undigested chances of reptiles/fish/eggs inside a coprolite? not this one, but many of the other pieces I have found seem to have pretty clear inclusions of things like turtles and other things.  I could be crazy also, but some of the inclusions seem to have something like skin still on them, which after research i noticed could be just lichen, but its strange that the lichen would just be on the inclusion and be a believable color as well. There also appear to be many many bite marks or teeth marks on them.  

 

My understanding is that my part of California would have been under water, and wouldn't be possible for dinosaurs to leave the coprolite. And based off the inclusions in the other rocks, it would seem to be a water beast anyways, or possible a large bird, ore maybe just something that lived by water. but not sure because like I said my area was below the sea back then.  It just seems so large for it to be from a sea creature and I would have thought if something pooped in the ocean. would not most of it disperse and break apart in the water before it sunk and was covered up?   Again, i have no clue haha

 

Let me know if you want to see some of the inlusion pieces or more1 photos of this one. Photo #4 shows what i thought to be skin on this one, but other pieces are more clear. But again I have no idea

Thanks for your time and I hope that a least one of you can help me out a bit!  Have a great day!

[Fossildude19]

@GeschWhat  @Carl

[DPS Ammonite]

Dinosaur coprolite material is unlikely as most dinosaur aged rocks are metamorphosed in the area. Closest dino fossils are from Panoche Hills in central California. Serpentine or metamorphosed volcanic rock is my best guess. Rock is best identified in person and not from photos. Take rock to geology department at Stanford or take to local gem and mineral shows for ID. You also could show it to the Peninsula Geological Society.

[ynot]

Welcomr to TFF1

I do not see any fossil in this rock. The description You give of a green mineral that turns white sounds like a mica that is drying out when exposed. Does the green come back when You wet it?

It could be a low grade serpentine or a chlorite schist.

The white lines are cracks in the rock that have filled with other minerals.

[Zesus]

Thanks guys for the fast replies!! wasn't expecting that speed.  The green i was referring to is the white you see in photo #1. the green part becomes much more green with water, but the white stays the same.  Ive attached some more photos i probably should have originally. Im curious what the shiny crystal looking things are. The first photo I added shows them inside the one chunk i removed that was sticking out. the crystals are the dark spots, they seem to be throughout.  Serpentine seems to fit best!   I definitely have schist on the property though, at least google images tells me I do haha as I compare and contrast.  And I do have serpentine, the serpentine just looks much different but i guess that comes in all shapes and sizes. I attached that below as well. serpentine is pretty cool stuff. this one piece looks like a wing , it was sticking straight up when I dug out some weeds.   Thanks again for the help and info!  Should I crack it open?  its so heavy and dense Im curious what it would look like inside. Maybe nothing.

 

 Also, is it ok to post some more rocks I have on my property for ID purposes. Specifically the other rocks I have that i think are coprolite? I think you will find them much more interesting.  Or should I start a new topic discussion? It does fall under the same topic. 

 

[JohnBrewer]

Can’t really help but welcome to the forum

[GeschWhat]

Welcome to the forum!

 

I'm not seeing anything to indicate that these could be coprolites. Keep in mind that many of the things you see online labeled as coprolites are not really fossil poo. There are generally four things I look at when trying to determine whether or not something is a coprolite. First and most important is location. Was it found in an area where fossilized body fossils are also found? If yes, then, I look at the overall shape. Are there sphincter/pinch marks or intestinal folds visible? Shapes can be obscured by erosion, and not all rocks that look like poo have fecal origins. So the best indicators are visible, identifiable inclusions. If there are visible bone fragments, scales, teeth or other bits of prey it is usually pretty easy to determine whether or not you have a coprolites. Lastly, I look at consistency.  Most carnivore coprolites will contain a lot of calcium phosphate - the same mineral that makes up much of our bones. It is usually very fine grained. If something is too granular, it is most likely not a coprolite. All that said, if a coprolite is siliceous in nature, it would be much more difficult to identify. I hope this helps.

 

 

 

 

 

 

[Sagebrush Steve]

7 hours ago, ynot said:

Welcomr to TFF1

I do not see any fossil in this rock. The description You give of a green mineral that turns white sounds like a mica that is drying out when exposed. Does the green come back when You wet it?

It could be a low grade serpentine or a chlorite schist.

The white lines are cracks in the rock that have filled with other minerals.

I concur with serpentine.  The polished area comes from when it was compressed under the earth and slid along against other rocks.  This is typical of what happens to rocks in a subduction zone of a fault.  Here’s a link to a recent post showing a similar effect (scroll to the bottom of the page and also Page 2).

 

[ynot]

6 hours ago, Zesus said:

Im curious what the shiny crystal looking things are.

Chlorite, a mica like mineral. Common associate of serpentine.

[Zesus]

Awesome, Thank you all for the input and welcomes. Serpentine seems to be the consensus. Im going to post the next one in a different thread, as it is much different in size and appearance, but again have no idea what it is.

[Carl]

Joining late, but I agree that it's not likely a coprolite. Lori, as usual, said it perfectly.

[Zesus]

Hey guys!  

 

So I cracked it open haha. Basically out of pure curiosity and also it's just kind of fun to open up rocks, maybe I'm weird. So here are some pictures if anyone is interested/cares. It appears to have some sort of "nodule" in it. I found it impossible to take to a picture that stayed true to the actual colors but the top one was taken inside, the rest outside. the white part is actually more blue, doesn't really come up in the photo but maybe you can see it. Likewise the dark green is a deep dark green, somewhere between the two different lighting. The rock seems to flake/fracture off if it gets chipped as opposed to come off in chunks.  I had three questions if anyone has the time to help. 

 

1. What is the nodule in the middle or why is it colored differently?

 

2. What is the blue white speckled part? (sorry for lack of adjectives and descriptors, I really am a neb)

 

3. Is serpentine still the consensus?

 

Thank you all for your help and I appreciate the time you take to help me out! My curiosity about rocks seems to expand daily. I wish I had on call geologist I could ring and who could come answer all my questions haha. Have a good day!

 

[ynot]

Still looks like a low grade serpentine to Me.

 

[Darktooth]

On 12/2/2017 at 5:52 PM, GeschWhat said:

Welcome to the forum!

 

I'm not seeing anything to indicate that these could be coprolites. Keep in mind that many of the things you see online labeled as coprolites are not really fossil poo. There are generally four things I look at when trying to determine whether or not something is a coprolite. First and most important is location. Was it found in an area where fossilized body fossils are also found? If yes, then, I look at the overall shape. Are there sphincter/pinch marks or intestinal folds visible? Shapes can be obscured by erosion, and not all rocks that look like poo have fecal origins. So the best indicators are visible, identifiable inclusions. If there are visible bone fragments, scales, teeth or other bits of prey it is usually pretty easy to determine whether or not you have a coprolites. Lastly, I look at consistency.  Most carnivore coprolites will contain a lot of calcium phosphate - the same mineral that makes up much of our bones. It is usually very fine grained. If something is too granular, it is most likely not a coprolite. All that said, if a coprolite is siliceous in nature, it would be much more difficult to identify. I hope this helps.

And don't forget the tongue test! That's my personal favorite!

[GeschWhat]

On 1/23/2018 at 5:19 PM, Darktooth said:

And don't forget the tongue test! That's my personal favorite!

Yeah...this one didn't look like it would have good stickage 

[Rainbowfh]

I know it’s been a while for this topic but, do you happen to still have this rock?