In reading some of the other posts on the economy and expansion models in the game I started thinking.

Right now there are three strategic resources,

There needs to be more.

These rare resources need to be tied to more than just specials on ships.   If galactic wonders, or some of the major planet buildings needed specific rare resources to function.. or to be built it would do several things.

1.  The player would have to be more strategic on building starbases for mining.   Rather than just focusing on building production worlds, or research worlds..  it could create specific worlds that do more specific things.

2.  It would tie the economy to something.   If the "Galactic Mint"  Could only be built if the Civ had Latinum or something as an example it would make money from something rather than just printing currency (credits)

3.  It would place finite limits on an economy or military.

3a.  These limits would bottle neck civs and force growth or military aggression...   Yor need space whale oil for a super replicator...      you have space whales that you protect and do not harvest in your territory (cause you are good and all that jazz)   Yor don't care...  murder death mayhem.. 

3b.  If mining certain resources say "Radiatiium 346 isotope" or "space whale oil" is tied to either pollution, possible disasters, or at the least ideology choices it could also impact game play...  Oh looky there is Radiatium right next to my main planet... if I mine it I can increase production my 400% on this other planet.... and kill 50% of my population or lose tiles... or some horrible cost.. ah well...  poor suckers.. MINE BABY MINE!!!

4.   It could create more options for trade or diplomacy... also UN stuff.

Thoughts?