I guess it depends what your definition of mining is. Shoveling, stripping, dredging, blasting IMO all mining.Is sand mined? I tend to think of it as just shoveled up rather than dug up, but maybe I'm wrong.
Another interesting topic. The Helpful Gardener (Scott) seems to break things down one step further. I like that. Fossil Food.Here's a thread in which perlite was discussed in conjunction with vermiculite: