Borax - discovered in Tibet, transported along the Silk Road - is a handy compound for use in ceramic glazes & slips. Also useful in cooking, cosmetics, and in the manufacture of fiber glass. The trade name '20 Mule Team Borax,' under which the partially-dehydrated salts of boric acid are still sold as a laundry booster, was first used around 1900 when Francis Marion Smith started using mules to haul the mineral out of Death Valley.
I learned this reading Desert Bloom, a beautiful recent article by Alex Ross making vivid the drama, the geology, the allure of this place - crucial reading for a potter, somehow. "The Death Valley that we see now did not begin to form until about three million years ago," Ross comments. "It has a raw, chaotic look, like an unfinished construction project."