Silverbear, it sounds like you have some Wyoming black Jade with
Magnetite, although the grey part should be the part the magnet
sticks to. I’ve cut quite a bit of this material and it’s a bit of a
pain to get a great polish on it. I usually hand finish using diamond
tape from my dentist. You can gold plate the magnetite for a nice
Karen Hemmerle who polished a bunch of Honduran Opal tonight and has
chrome oxide fingers!