oh yeah, also, btw
best way to grow pure crystals of any freebase chemical is to extract into near boiling solvent, dry it with a drying agent like magnesium sulphate or sodium sulphate (MgSO4 baked in the oven is the cheap and best, grind it finely, only a small amount is required, it's just the tiny bit at the bottom of the jar it needs to pull out of the mix)
and then once your warm solvent is dry, ideally, heat it again to near boiling, and put it into a vacuum flask or similar highly insulated container, and then put that inside the freezer, preferably sitting on some spongy material that will stop it catching the vibrations from the compressor
that will get you big gnarly chunky crystals, and after you pour off the solvent, after a few days to a week, the purity is extremely high and it only takes minutes for most of the solvent to be gone, an hour to be sure
this is standard practise in organic chemistry laboratories
yes, why the heat again?
you want to heat it until it starts to get a bit milky or some solids start to form, this tells you it's saturated. then ideally it stays warm and this gives lots of time for the crystals to form slowly and the impurities don't get into the core of the crystal, the longer you can make it stay warm the better
also, they do the same thing when baking photovoltaic cells... the bigger those crystals are the more efficient they are