There is a major problem with minerals atm, the way it is currently handled seems to create a major excess of purple minerals and a lack of yellow minerals. I believe there could be two possible reasons for this....
First there is something wrong with the code which makes purple crystals more common and yellow ones less common, thus creating an excess of purple and a lack of yellow. This would be due to poor programming and while I can't say for 100% certain this is true I do believe it could be partiall true for causing this problem (I seem to see way fewer yellow then any other cystal formation, can't say purple is way ahead of everything else though).
Second, people have an affinity for purple crystals, I don't know why exactly. My best guess would be because of naming them purple they named them "dark matter" which compared to the other minerals sounds fairly cool. I know it got me excited about grabbing purple crystals when I started playing, vs other types.
The second reason brings me to the problem, minerals can only be picked up 1 per person per floor, and each person on that floor has the ability to only select 1 color/size. This means if there is some reason people like 1 crystal over another the entire game can become unbalanced, which it has. Purple is way too common, purple cyrstal themed stratums, especially before a boss stratum, happens way too often. I realise that this weeks jelly and roar twins gates were both preceeded by beast, not sure how that happened but maybe the purple ones were saved for the vana gate.
There is a simple solution, imo, to fix the whole crystal problem. Make it so crystals aren't carried to gates, make them an item like every other single item in this game is; you pick it up and you get it in your inventory. Now I realise this means the number of minerals on levels would probably have to be dialed down, but it would remove the discrepiency that exists towards certain mineral types.
I bring this up becuase the idea of gate construction is the foundation of this game. But if we are unable to control the gate construction because there is 20% more purple crystals then any other type, how are we supposed to be able to play. I don't want to spend 5 months saving up crystals so I can control the outcome of one gate.
TL;DR
Make minerals a pick-up to inventory item to remove the bias towards purple crystals.
Is the bias toward purple caused by players? I was under the impression that purple was just worth less and yellow worth more than the others. I don't see purples as being more common than anything else, and people always take the biggest crystals when they can, purple or not. And I don't see a noticeably high number of people taking purples rather than any of the other colors.
I like the knights carrying crystals on their backs, though. It makes things interesting. So I don't like the idea of a pickup inventory item. But I definitely agree that something needs to be done about gate construction. It really doesn't give people much control, because the equalizing prices make all crystal deposits that happen up until right before the ending time pretty much meaningless.