The stones were- I think- quartzite and someone had brought them into class to demonstrate how people in the Stone Age might have started a fire.
You wrap the quartzy stones in wool,
Knock 'em together; they'll give you fire.
The classroom is all hush and dark.
I knock and raise the ghost-green light
That's gone as quick as the meteorite
I saw scrawl over Pegasus.
Did I see it or did I think it?
I sniff the stones. They smell of burn.