General

How do I make powders Herbalism I was reading a guide about recipes that said herbalists can make oils OR powders with certain items. (I guess that sounds a little ambiguous, so bear with me...) How can I make colored powders, to be used in alchemy recipes later? It's driving me nuts! Some of the herbs I've picked up say "It can be refined to obtain a rare magic powder (brown/yellow/black/purple/etc.)" How do I go about this... refinement? I know I can make oils, but what about magic powders? Thanks.