We lived on land in Louisiana that, if you dug down a few feet, you came to a layer of clay. I liked messing with the clay. We had no kiln or anything like that, but I did experiment with shaping things. The clay was muddy looking, but it behaved differently than mud. It held together. It had a glossy look to it. And instead of absorbing water like dirt did, it tended to block water. Parts of the yard that had clay beneath stayed soggier after rains, the layer of clay preventing some of the drainage.
Many Native American Indian tribes have been renowned for their skilled and beautiful pottery work. The color of the materials typical of specific tribes likely were affected by the mineral makeup the clays of their locations.
Before we had such easy, far-reaching means of transportation, and before we had big box construction material franchises like Home Depots and Lowe's, one might have noticed that various towns and locations had buildings and walls of brick that were mostly of the same color. In south Louisiana, we had quite a few churches, school, and hospital buildings in the 1950s that were of a particular shade of red brick. That might have been because the bricks used were of a local clay.