We've been celebrating 150 years of the Periodic Table. This episode, the rise of aluminum! The element is incredibly common, but was once hard to extract. That made it more valuable than gold in the 19th century. NPR's Scott Neuman gives us a short history of aluminum. Or is it aluminium? (We'll also give you the backstory behind the confusion.) Follow Emily Kwong on Twitter @emilykwong1234. Email the show at shortwave@npr.org.