Quartz

["Irwin Stone" <irwinstone@zzzzzzzzz>]

Eric

As a suggested in a private email, I'm fairly certain your stone is
quartzite, a substantially different animal than true quartz.  The basic
geology of the stone, as I understand it, is the stone used to be sandstone,
and it was metamorphicly (?) changed by heat and/or high pressure, basically
baking the sand into a harder stone than it used to be.

I've never carved quartzite, but have sawn & chiselled a lot of it. It works
pretty easy in my experiences.

David