Where did you find this stuff?
Looks exactly like the stuff i found beneath my old intake. I swapped an LS6 intake for my LS1 intake. Underneath the intake i found lots of this exact material. I though it was sand or some ****, there was an abundance of this stuff.
Poor Camaro, cleaned it all up and moved on. It use to have dexacool in it. Switched to the green several months before i swapped the intakes.
My grand am also had dexacool in it. Must be why the intake was leaking coolant..