NautilusVW, a member of my home forum put forward a very interesting, though surprising theory about the nature of mithril. Let me will quote it here:
What metal could have actually been the Dwarvish "true-silver", the mithril? Tolkien doesn't give much detail - just outlines its chief features: strength, lightness, silver-shine. And, last but not least, impossible to tarnish. Various "crackpot" theories have equated mithril with aluminium(which unfortunately can't be extracted directly), or other exotic materials like an yttrium-silver compound. I'd say the metal that fits best the description(light but harder than steel, chemically inert hence impossible to tarnish) it's nothing more than titanium. Twice stronger than steel and with higher melting point, just slightly heavier than aluminium, immune to corrosion, it can be deemed the noblest of metals.
Pure titanium is about as strong as steel yet nearly 50% lighter. When added to various alloys, its hardness, toughness and tensile strength can be increased dramatically.
Titanium is immune to corrosive attacks by saltwater and marine atmosphere and exhibits exceptional resistance to a broad range of corrosive gases, acids and alkalis. Titanium is immune to microbiologically influenced corrosion and is physiologically inert and hypoallergenic. Titanium is virtually non-magnetic, making it ideal for applications where electromagnetic interference must be minimized.
Titanium weight: 4500kg/cubic meter
Iron weight: 7870kg/cubic meter
Titanium is a lustrous grey metallic element
The original discussion is here: http://b2.ezboard.com/fmordor69452fr...icID=228.topic
I hope I have not bored you to death with this, but there apparently are lots of similarities between mithril and titanium.