It's gray, shiny, and brittle. Fairly light for a metal. When he touches it, he instantly feels that he could use Feruchemy on this. Perfect.

"Congratulations," he says. "You've managed something no-one else has since ever.

This would be more than enough to handle Thorn with, but of course I'll want a supply for general use. How efficiently do you think you could transmute something like this?" He hands her a piece of zinc. It's slightly bluer and a touch heavier but otherwise similar.