"Check...my pockets?" That's a weird suggestion, and slightly suspicious, but Barcus pats his waistcoat gamely, finding nothing unexpected. "Well, I have a coal sample but I don't think that's what you're looking for. It's good anthracite, though. Actually, here, it's not a nice magic rock but you can hold onto it until we find yours, if you like."

The coal sample is, in fact, very tiny. About the size of a thimble. But it doesn't matter that much if it gets lost, and it's in a little broadcloth bag. Barcus offers it up.

"It sounds like Soarrie might be mostly calcite," he goes on, starting to lead the way down the street without explaining where he's going first. "I wonder if Dorrie might be an agate of some sort--"

And he's off, launching into chatter about the types of minerals that can be found in various types of stone.