: P.s i think it is Ti...

The only reason that I disagree with mithril being titanium is that titanium is very plentiful, though difficult to refine. If the dwarves knew the process (and there is nothing that says they didn't) then mithril wouldn't have been found only in Khazad Dum and Numenor. The dwarves of the Iron Hills and Erebor would have also had access to mithril through the refining process and mithril would have flowed from those regions as well as any other dwarf warrens.

-RR