"Its worth was ten times that of gold, and now it is beyond price; for little is left above ground, and even the Orcs dare not delve here for it."
Mithril, the ultra-light, ultra-strong and ultra-rare metal of Middle Earth, has always fascinated me. When I first read Lord of the Rings I assumed it was magical, but I re-read the descriptions of it, and guess what – mithril is never explicitly described as such. It's just very rare. "Magical" in the poetic sense, like gold.
If mithril is a "real" metal, not a magical or fictitious one, what could it be? I have an inkling, and it's both prosaic and surprising. Let's go through all the known properties of the stuff:
• Very malleable; that is, able to be shaped without breaking or cracking.
• Very lightweight.
• Harder than steel.
• Similar in appearance to silver.
• Resistant to tarnish and corrosion.
• Very, very rare.
There is only one metal that fits all of these characteristics perfectly: Aluminum.
Yes, Aluminum. Aluminium is very malleable – check. That's why it's so easy to produce as cooking foil. Aluminum is very lightweight and much stronger than steel – check. In fact, jet airplanes couldn't fly without aluminium. Similar in appearance to silver – check, and resistant to tarnish and corrosion – check, thanks to the phenomenon of passivation.
"But wait a minute, Mr. Smart Guy", you say. "Aluminium is about as rare as dirt". Ah-hah. Yes, that's true – now. But, before the late 1800s, no one knew how to extract the metal from its ore. The big secret, apparently, was zapping the ore with electricity at a the right time during the smelting process. Before people figured that out, aluminum was literally rarer than platinum. So rare emperors served their most important dinner guests on aluminum, while everyone else had to make due with plain-old gold.
There is still the question of "ithildin", the magical stuff that could only be seen in moonlight, which the Elves made from mithril. My guess is ithildin is probably mithril with some kind of enchantment worked into it – how or why the enchantment worked, and why it only worked on mithril, I have no idea.
But it seems pretty clear aluminum is a strong potential candidate for mithril, at the very least. And I don't think it cheapens or "takes the magic out of" mithril; just the opposite, in fact. If Tolkien really did mean for aluminum to be the secret identity of mithril, he was making a pretty powerful statement about how much perceptions and scarcity shape reality. Something we take so utterly for granted was, a thousand years ago, the most priceless stuff on Earth.
Think about that the next you toss a soda can into a recycling bin! The atomic number of mithril is 13.