Hi, I teach high school chemistry, and I'm looking for a recommendation for educational videos or documentaries on mining and refining metals. I'm particularly interested in videos which emphasize the chemical reactions, though I'll take other recommendations also. I'm also particularly interested in videos which compare production methods for several different types of metals, rather than just one. Many of the videos which come up with a google search are amateur gold mining videos, which is a rather limited specialty for my purposes.
Dave