Debbie, thanks for your thoughtful post. I appreciated your helpful comments - especially regarding the bort, which I know little about. I will certainly add this to my workshop.
I can relate to your comments on soapstone. I always use a respirator and face protection when I carve. I have a downdraft table with dual fans and filters behind it. I have enclosed the table (actually an old desk which I modified) with a plexiglass shroud on four sides. I run not one but two air filtration units in my garage/shop, and of course the old reliable shop vac for general dust management. I only use power tools for the initial roughing out of the stock material - and still the dust is overwhelming. My conclusion relative to the dust supports your own experience! However, since soapstone is so soft it allows me to prototype designs and work on aspects of technique.
Since obsidian and other harder material is readily available in Oregon I am striving to learn how to work with this material. I am practicing with basswood and soapstone to develop a small (2" dia. ) ammonite replica and need to cut a few slabs of obsidian for my project. Cutting the basic round shape from the slab is relatively straightforward, but carving the spiraling curves of the ammonite itself is presently challenging. I need to determine how much to "oversize" my spirals in order to shape them properly. I am trying to approximate a Fibonocci sequence in defining their progression.
Another thing I am trying to determine is the selection of a good reference point for my carving. For example, in carving waterfowl from wood blanks one learns quickly to use the bird's bill as a reference point for scale. I think on an ammonite one can either start at "the beginning" - which is the small circular part at the very center of the shell - or at the very end or "occupied" part of the shell. In either case the spirals work to the opposite end in a formal sequence of curves. Thus far working from the center out seems to make the most sense and it "feels" right to me.
Finally, your remarks on marking up the raw stone are much appreciated as well. I use a traditional pencil for center lines and a sharpie to define basic cut lines. Have you tried using a special colored pen - silver, bright yellow etc. - on darker stone? I do tend to get lost in the weeds when in comes to accuracy - part of me wants to be as realistic as possible, while part of me likes working with representation and abstraction. Experimenting in expendable materials will hopefully help me to find my comfort zone in this regard, while fooling around with the rock itself will help me to learn more about the material and ways to work with it.
I appreciate your comments and hope you will not feel shy about offering more!