Harrison wants to find out if he can really make gems from charcoal or gold from lead. A geologist guest shows him that other kinds of rocks are cool too, especially meteorites. Rocks rock! “When you squish a piece of coal, how does it turn into a diamond?” Challengers pan for gold in a stream, just like old-time miners. But watch out for fool’s gold! Harrison rappels down into a cave to see how stalactites and stalagmites are formed.