Bauxite proppant is an aluminum ore from which most aluminum is extracted.

Ceramic proppants are engineered from either non-metallurgical bauxite or kaolin clay to have relatively high roundness, sphericity and size that can withstand very high levels of downhole pressure.
Bauxite proppant is an aluminum ore from which most aluminum is extracted. Kaolin is a mineral clay that also contains aluminum, but not at ore grade levels. Through a process called sintering both materials can achieve superior strength characteristics.
Before sintering, the ceramic material is crushed, pelletized and sieved into specifically sized particles. Sintering occurs in high-temperature kilns that bake the sorted particles to decrease their water content and thereby also change their molecular structure, rendering them more spherical and more uniformly dense.