Gersdorffite is a fairly rare nickel arsenic sulfide. While it is found at a number of localities, the bulk of well crystallized samples (when you see them) come from the Bou Azzer region of Morocco.
This year a few of the Moroccan dealers had examples of the species, I'm guessing there was a pocket of the stuff that got split up among a few of them--there would not have been more than a few flats in total. Most were in rather poor condition or way too large, but I did select one decent looking piece. It's not perfect, but fairly sizable compared to what you would normally find.