I have some Gray soapstone and have made a pen using it. It turns okay, just sorta becomes a powder. If you PM me with your address, I'll cut some and send it to you. It is hard on the tool, but not more than Oak Burl, or Ash Burl!
Here's the pen I did with it.
I think the next one I do with this stuff, I'll use a Satin Gold or Satin Chrome kit with it.