Pigmented (Pattern) - unsure if leather or vinyl vomit stains - for 'Sack'

Roger this chair has too perfect of a pattern and I think it is vinyl. I was able to get a swatch from underneath, it buns (doesn't go out, dried like plastic but I could smell a little protein while it was burning. The back side looks like and feels like ultra suede or a very fine leather, but I think the top is a vinyl.
Is there a definitive method to know for sure weather it is vinyl or leather?


Attachment 5281
7-7A overall seat

Attachment 5279
7-7B close up of stains

Attachment 5280
7-7C further close up of stain

>>> Is there a definitive method to know for sure weather it is vinyl or leather?

Reference to “7-7C further close up of stain” it could be a combination of both.
In this picture it shows that the grain is embossed with a heavy material (vinyl or synthetic) while the lower groove or valley of the grain look more absorbent, could be the protein leather based just like a ‘Bicast’ leather.


>>> to know for sure weather it is vinyl or leather?

We have to peel them apart to see the cross section besides the burning test.