Come on, people. Let's all be grabbing yellow and green minerals to boost Jelly production! Leave dem reds alone, or sell them in the far mineral dump; nothing but yellows and greens for the upcoming gate!
Imagine a blissful world of hacking Jellies, level after level. Coming back to Haven covered in sweet, sweet syrup instead of bitter brimstone blood!
GIMME LICHEN COLONIES! GIVE ME RANDOM HUGE ROYALS IN THE MIDDLE OF GATES! GIVE ME THAT BETA TOXIC ROYAL! COME OOOOON!
Project uJelly again?
The problem with farming Slime stages nonstop is that mineral distribution in Slime stages will favor Fiend and Shock minerals. This was a much worse problem back when Red Carpet Runaround was basically the best money-farming stage in the game... but running the Royal Jelly Palace over and over meant that you'd be getting more red, purple and blue minerals than the green and yellow ones.
If you want to collect the minerals for an all-Jelly gate, you'll need to search in strata that are not made of green or yellow minerals. Specifically... you'll need to go into Fiend strata.
(Do people still mass-farm the Royal Jelly Palace? It might explain the continued prevalence of shock and fiend.)