My guess would be intense heat with lack of flame. It seems the chip plasticized to the point where backside conformed to a fabric or irregular shaped container and the front was viscous enough to allow the impression without cracking had it been simply a pressure application. the lack of charring would seem to indicate little or no direct contact with flame. I am also rethinking the token theory as it appears the impression is a smaller diameter than a standard token or even a 39-40 mm chip.

I am trying to earn my Palms CSI chip merit badge