Alchemy Recipes

So am I reading this right, to make a Dark nisrock I need 4 Adamant POWDERS and 10 Black POWDERS, 30 of those Crystals, then I can use a Diamond and a BLack Crystal to add atk?

No, as the blurb at the beginning states the "Powder" column may include plates. A metalic descriptor is a plate. Powders are chromatic only.
The column is just named powder because the vast majority of items in it are powders. Only weapons use anything else and weapons are outnumbered 5 to 1.

You need 4 adamantium plates, 10 black powders, 30 of the best middle crystals and then you have two upgrade slots, plus stimulators, to work with.