What epochrpg mentions is something that originated in Magic of Faerun, though it probably was reprinted in the Magic Item Compendium. Near the end of MoF it has special materials for weapons and armor in Faerun, including adamantine for example, but also alchemically/magically-treated gold and other precious metals.
There's a sidebar on heavy weapons; items made from the aforementioned gold, platinum, and such are considered heavy weapons. You need a specific EWP feat to use such a weapon without penalty, and it can't be used with Weapon Finesse. The damage increases one step, but that's a terrible trade-off for a quarterstaff. Less effective than a two-bladed sword, but probably heavier and still requiring Exotic Weapon Proficiency.
However, MoF has a restriction that only weapons made primarily of metal may be made with materials that would make them heavy weapons.... So a spear or quarterstaff isn't supposed to be made that way.
An exotic quarterstaff made of metal would probably be 1d8/1d8 with 20/x3 crits (effectively similar to twin warhammers, as a two-bladed sword is essentially twin longswords).
A simple quarterstaff made of metal.... Would probably be rather thin so as not to be overly heavy, and still difficult to handle. 1d8/1d8 damage and 20/x2 crits, with a -1 or -2 penalty on attack rolls even if proficient. Don't know if I'd even make a simple version out of metal though.