A FOAF recently did another xylene pull from a batch of MHRB that had been sitting around for awhile and thought to be nearly exhausted. He was blown away when close to a gram precipitated after adding FASA. However, these aren't the nice white fumarates gathered during the previous pulls. On the bottom was a layer of orange and very waxy fumarates, and on top were fluffier crystals like the white ones, but very noticeably yellow in color.

Has anyone else had this happen? Can these be used as is, or should they be further purified somehow?

Does anyone have experience using these in pharma? If so, is there any noticeable difference between those and purer crystals?

I've obtained dark reddy fumarate salts from month+ old MHRB, these were initially quite gooey and took a while to solidify & dry out. They're now powderised but I haven't tried them, only 80mg was recovered in any case. No fluffier whitey yellow crystals were recovered from this fasa pull though, probably all exhausted from previous pulls as they were yellowy.

SWIM doesn't think there's anything wrong with your fumarates, but when he dries his, he does it in the oven and gets hard rocks, powder and a minor stickiness (like sugar or ascorbic acid, probably due to excess fumaric acid). A water wash as suggested by bufoman: https://wiki.dmt-nexus.me/FASA_Alteration_of_Final_Purification should get your crystals plenty pure. SWIM doesn't know for sure whether an acetone wash beforehand is at all necessary, but he happened to have done that prior to using the method above, successfully.... SWIM would guess that's it's entirely unnecessary, though.