The earth is covered with rock, gravel, sand and clay. What differentiates these is the size of the particles and the constituent minerals. Clay has the smallest particle sizes and shapes. So water and organic matter lubricates the smooth particles so that is can be formed onto a ball or roll in your hand. This cant be done with sand.
In rural areas people know where to dig out usable clay for different uses. Clay pots, building adobe walls, cosmetic and medicinal clays.
In urban areas, clay is available for many uses. For the purposes of Makesa, we focus on what clay can be used for to make products, especially clay pots and the like, lets call it pottery.
The clay is divided into 4 main groups, which are separated by firing temperature: