The crown payouts should be dynamically priced so that there's incentive to get the rarer minerals rather than just getting the biggest ones (which happen to be reds and yellows due to the bum-fucktarded spawning algorithm.)
For example, for virtually all the gates open right now, in this system crown rewards would be:
Least common: Purple: +10
Less common: Blue/Green: +5
Common: Red: 0
THEY'RE EVERYWHERE: Yellow: -2
People who take note of this and actually read will avoid taking red/yellow and pick up the less common cool colors to maximize their crown pay for depositing minerals.
You're free to spend your crowns and make it so.