The other day I commented on a post on Facebook, recommending igneous rocks for a working. Thinking further about that, tho', I realized that was a holdover from growing up in the Midwest, and not what I'd do myself, now that I live in the Appalachians.
The bulk of Illinois land is sand loam - six or more feet deep of it. There are occassional streaks of sand or clay, and occassional stones (usually granite, scraped up by the glaciers when they dug out the Great Lakes in the last Ice Age. As a result of growing up there, and starting my practice there, my 'mother tongue' of land magic is based on that.
But I'm no longer in Illinois. I'm not even in the stoney silt/clay mix of the piedmont of Maryland anymore. I'm in the Appalachians, with a Duffield Clay variety of soil. I've posted before on how my local soil, when worked by hand for gardens, rewards hard workers with nice chunks of quartz.
The local clay also, I've discovered, can make fine talismans, amulets, other magical objects, if dug up and purified. And THAT is what I'd now use in place of chunks of igneous rocks in the same workings.
What's your land base like?