Gypsum Flour Pellets Reviews

I had been using the gypsum flour but these pellets have replaced that product. I have concerns that the pellets are not as high a quality as the previous product. There seems to be some rock mixed in with quite a bit in some samples. What are the pellets composed of and how much calcium is in them? I inquired and was told they are pure calcium but that does not seem to be accurate. My other inquiries have been ignored. To bad.