Spherulite?

[PrettyOkay]

I found this near a fossil site of a 53 million year old lake, located in the Thompson area of British Columbia. It looks like a thin layer of bubbling glass, the outside of which is scorched. I've never seen anything like it and given the location it was found, I'm very curious about what it is!

[Geologyhound]

It is a little hard to tell from the single picture the composition of the matrix.  If it is naturally occurring, then my initial reaction is your “bubbling glass” may be a layer of botryoidal agate.  If a corner of that layer can scratch glass, that would support this theory.

[PrettyOkay]

Thank you! It successfully scratched glass so your theory seems to be correct. I took a few pictures of the piece that broke off for additional reference

[Geologyhound]

Yep, the new pics definitely look like an agate layer on the surface of void areas.  When water migrates through pore spaces of a rock, it is under higher pressure and can hold more minerals in solution.  When the water enters a void, the pressure drops and the water cannot hold as much mineral content. So, some minerals precipitate on the surface of the voids.