Book Three: "They burned it. I can't believe they burned it. It's been here for centuries." "Shut up, Graden." "Calm yerself, Chesh. Jest because you loved this plece and now et's gone doesn't mean yeh have the right teh teke it out on us."
Fordite or Detroit Agate - if this means what I think it means, it is the packed layers of paint off the wall of a car-painting facility. Siince the paint is enamel and baked on, it cuts and polishes up nicely.