This was in a large astronomy collection I recently bought, have no idea what it is or even if it is related to 'space rocks'. Maybe it's a naturally forming crystal or some such.
In any event, anyone know what this is? About 4.75"/5" in diameter, about 3/8" thick in the middle, 1/4" at the edge. Looks to be a sandwich of some sort, pattern looks to radiate from the center.
Thanks in advance for your input.