one thing i have found out is that iron meteorites don't try to orient themselves when you place them on a magnet. there were other pieces of metal in the mix but they do want to orient to a specific position, often standing on end. because of the grain orientation. Anyway, I don't automatically assume they are meteorites but I would bet heavily on it that they are. it is hard to do much testing on a piece so small. I don't put much faith in nickel testing, although i have a kit.
One more thing is that iron meteorites don't become a magnet after being placed on a magnet. man-made iron does. The little pieces do not attract other stuff, black sand, etc. so another good indicator but still not positive proof, I know.