It doesn't flake off the stone, it is in there and has to be pulled out, but does separate easily. It is almost like fanning a magazine with your finger. Some of the pieces I did pull out looked almost like a glazed sliver of glass or plastic almost transparant, and some were harder like a very thin piece of tin or the small springs inside of a watch.
I found another stone today with these very dark square posts coming out of the center, I cracked the rock to get some of it out and placed a magnet on it and it stuck to it. This was out of the same batch where I found the others I pictured. I just wanted to add that in to help the info.