Doesn't look like "rocks" at all to me.

Appears to be a piece of cement block. Very light and airy to give good R values. Rocks don't have big flat surfaces like that.

Whatever she was carrying, it was man made, and therefore there is no way to know how heavy it should have been without physically inspecting it. While I'm always up for exposing the deep state and their lies, this doesn't seem to be evidence of anything.