Help identifying fossil/bone vs phosphate

[Kbsib]

I am learning the differences between rocks, phosphate and fossils. All are abundant on the beach here. This piece has thrown me. There are areas that look bone like. Other areas not so much. The two holes and sheen on parts of the item made me not automatically dismiss it. However it is very worn. Any special ways you use to distinguish between rocks and fossils in a situation like this. I’m learning and both success and mistakes teach me something. Thanks!

[hemipristis]

All of your specimens are phosphatized bone. Each exhibits the porous texture of bone (think "marrow")

Edited March 6, 2023 by hemipristis

[Kbsib]

I’ve never heard the term phosphatized bone but will be researching that now. Thanks for the ID. It explains some of my confusion. I could see the porous texture but there was very little smooth surface. I’m guessing the bone is just very worn.

[suz]

Thank you for posting this. I have been struggling with the exact same. So helpful! 

[Mahnmut]

Hi,

the mineral part of bones is phosphate (calcium phosphate) in living animals. (there may be exceptions, but I am pretty sure its true for most tetrapods).

(Most mollusc shells are one kind of calcium carbonate ore another -calcite or aragonite. The single celled organism Acantharia even builds its skeleton from Strontium sulfate.)

But not all fossils preserve that bone phosphate, often the bone substance gets replaced by other minerals like calcium carbonate or silicates.

On the other hand, in places where there are many bones and organic remains, (think bonebeds, but also bird guano that contains the phospahte from the fish the birds ate) not all the phosphate is preserved in the form it initially had but gets washed around and forms concretions, nodules, crusts... so chances are good that where you find bone fossils in their original (or similar) phosphatic composition, there will be a lot of other phosphate around.

Often the calcium in the bones will be partially replaced by other metals like iron, giving the phosphate fossils a darker color. Iron phosphate (and maybe manganese) can also turn bones greenish or blue (I wish I could find one of those...)

-I guess phosphatized bone means that the non-mineralized part (collagen etc. ) of the bones is also replaced by phosphates.

Best regards,

J

Edited April 20 by Mahnmut
second thought

[MuckyBottles]

On 3/5/2023 at 8:36 PM, Kbsib said:

I am learning the differences between rocks, phosphate and fossils. All are abundant on the beach here. This piece has thrown me. There are areas that look bone like. Other areas not so much. The two holes and sheen on parts of the item made me not automatically dismiss it. However it is very worn. Any special ways you use to distinguish between rocks and fossils in a situation like this. I’m learning and both success and mistakes teach me something. Thanks!

crazy as it sounds, lick it..if it sticks its a fossil.

[Ludwigia]

5 hours ago, MuckyBottles said:

crazy as it sounds, lick it..if it sticks its a fossil.

No offense, but this is an old maid's tale. Anything porous sticks, irregardless if it's fossil or not.

[Doctor Mud]

Definitely bone. You can see the cancellous bone structure or “marrow”

 

If I’m not sure I take a look under a microscope - a hand lens would work. Most of the time it is clear without this step. Sometimes where I’m hunting you get fossil wood in concretions that really looks like cetacean earbones. Im pretty good at recognizing it now, but had one recently that I had to check. 
 

A hand lens is a good thing to take in the field. One with a metal frame that you can wear around your neck on a strap. 
 

 

[MuckyBottles]

2 hours ago, Ludwigia said:

No offense, but this is an old maid's tale. Anything porous sticks, irregardless if it's fossil or not.

offense taken, im an old man.

[digit]

On 3/6/2023 at 10:37 AM, Kbsib said:

I could see the porous texture but there was very little smooth surface. I’m guessing the bone is just very worn.

This item is a good example of a weathered piece of fossilized bone. Keep in mind that the outer part (cortex) of bones have a smooth surface which is called cortical bone. The inner part of most bone is spongy and called cancellous/trabecular bone. Except for special cases like dugong/manatee rib bones which are solid and dense throughout (as ballast to counteract their blubbery bodies so they don't float around the surface like a diver in a thick wetsuit). Your find when it was less worn would have been skinned over with a layer of the smoother cortical bone. Erosion has removed the outer surface from much of the bone revealing the more spongy internal surface. The combination of cortical and cancellous texture is what we look for when trying to determine if a worn down rock might actually be a tumbled and smoothed fragment of bone.

 

Fossilized bone can change color based on the minerals in the environment when it was fossilized. In Florida we often see fossils in a variety of colorations: white, cream, tan, chocolate brown, grayish-black, even bluish-purple tones. All this variation can be present at a single fossil site. The blackish-gray coloration so commonly seen in many shark teeth (think megalodons) is often found in areas where there are phosphate mines.

 

 

Cheers.

 

-Ken