is this a fossil ?

[Andy W]

Hi

found this on at Whitby on the North East coast of England.

Not sure if its a fossil or just a strange shaped rock !!

Its about 6 x 9 inches

Any help would be great.

 

Thanks

Andy

[Fossildude19]

Looks like flint to me. I see evidence of conchoidal fractures.

Just an odd shaped rock.

 

[hemipristis]

More likely a lithic tool artifact

[M Harvey]

Looks like low grade obsidian to me.   

[Harry Pristis]

Those parallel flake scars suggest human alteration.  Obsidian flakes can have an edge sharper than possible with steel.  NA could have used flakes from this core for skinning small game or for other purposes.

"Obsidian is used by some surgeons for scalpel blades, as well-crafted obsidian blades have a cutting edge many times sharper than high-quality steel surgical scalpels, the cutting edge of the blade being only about 3 nanometers thick.[34] Even the sharpest metal knife has a jagged, irregular blade when viewed under a strong enough microscope; when examined even under an electron microscope an obsidian blade is still smooth and even."

[debivort]

Doesn't look like obsidian to me. Given collection locality, I suspect it's a pyritized limestone nodule with odd color balance/photo contrast. @Andy W Can you get us some better photos, with greater resolution and natural lighting?

[Harry Pristis]

33 minutes ago, debivort said:

Doesn't look like obsidian to me. Given collection locality, I suspect it's a pyritized limestone nodule with odd color balance/photo contrast. @Andy W Can you get us some better photos, with greater resolution and natural lighting?

I don't know what a "pyritized limestone nodule" might be.  I do know that neither pyrite nor limestone produce conchoidal fractures.  Tell us more about your suspicion, Debivort.

   I am not sure this is obsidian after looking at it again.  I guess it could be black flint from the east coast of England.  

[abyssunder]

In my opinion, it's a black flint, as it was said, with nice conchoidal fractures and attached marine tube worms remnants. 

[debivort]

5 hours ago, Harry Pristis said:

Tell us more about your suspicion, Debivort.

It strikes me as similar to how some N Yorkshire Jurassic nodules like this one break, for example:

from this video at 19:11 

 

But Whitby is not my home turf. I suspect a local expert will know for sure.

[hemipristis]

Location, rind, luster, texture and fracture indicate black flint

[Ludwigia]

To get back to the original question, in my opinion, this is not a fossil.