@MoodyBill: so NOT Ethanol?
There are folks in this thread who are crystallizing THCA out of ethanol. Either as the sole extraction solvent, or after winterization.
There are also folks who are seeing crystals during their ethanol recovery, who are probably NOT crystallizing THCA.
there is a also VERY similarly named thread where the nature of the non-cannabiniod crystals are being discussed: Ethanol crystals? (also some actual cannabinoid crystallization)
If you’re deliberately crystallizing out of butane/propane, then you might want to check out: Only The Strong sauce tek and/or it’s associated call for pictures: OTSS When To Cap, Request for Pictures
there is also a thread on using acetone: Acetone crystallization of THC-A
and a discussion of seeding: Seeding which is relevant no matter what solvent system you’re using.