Much of the Kaolin we use in the US comes from South Carolina & Georgia.
There are lots and lots in ingredients that go into Clay and Glazes. Kaolin is a common one that has so many uses.
Kaolin (China clay) is naturally occurring soft clay, first discovered at the Kao-Ling Mountain in South-East China (its very own namesake.)
It is a white, or off-white, hydrated aluminium silicate mined from mountains and gathered from tropical riverbeds. Its colour varies from white to dark brown and we mostly use the lighter variety in our products.
18th century French Jesuit missionaries sent samples of Kaolin to Europe from China to help illustrate how ceramics were made there.
Kaolin was also a traditional remedy for upset stomachs in South America and is still used in intestinal medicines today for its ability to absorb water.
A versatile material, kaolin has a multitude of traditional and industrial uses. Most of the kaolin mined today is used for making paper, ceramics, and in the manufacture of make-up and skin care products.
In cosmetics, kaolin cleanses and exfoliates dead skin cells and debris from the skin's surface. We use these qualities in our solid facial cleansers Aqua Marina and Herbalism.Kaolin adds absorbency, texture and bulk to cleansers, face masks, soaps and dusting powders.
What is Kaolin? - Industrial Minerals Association - North America
Digital Fire has a good description