Ordo is one of the more useful Primal aspects. While extremely scarce in "pure" form, use of a centrifuge can easily extract it from its plentiful compounds.
Ordo essentia is used in several key infusions and crucible recipes, but the most prominent is its use with Metallum for "ore purification": Converting iron and gold ore blocks into native clusters with double the yield.
Ordo is found directly in few items: Silverwood logs, Smooth Sandstone, or droppers. More often, it will be centrifuged from Motus, Instrumentum, or Potentia. (Machina can also be double-centrifuged for 50% Ordo.) Another option is Vitreus, which may be surplus from other work such as distilling emeralds. Formerly Gelum and Metallum were sources, but this was changed in 4.2.2.