The mineral nnullite (3Al(2)O(3)2SiO(2)) is frequently used by the industry in the preparation of refractory ceramics. However, it is uncommon in nature and, therefore, synthetically manufactured. The commercial mullite is synthetized from kaolinite + Al2O3 (gibbsite, bauxite), making the synthetization expensive. For that reason, naturally occurring deposits that can be utilized for the process are sought for. The Micaya deposit, located outside La Paz, Bolivia, is composed of a layer of kaolinitic shale hosted within the Vila Vila Formation composed of Devonian coarse-grained sandstones and siltstones. The shale is composed of quartz, kaolinite, muscovite and feldspar. The kaolinite can be separated from the shale by gravity separation, thus decreasing the SiO2 content and obtaining a new product with a higher Al2O3 content. The two major components (quartz and alumina) are then subjected to a calcination process at high temperatures in a suitable ceramic firing programme and results in the formation of mullite without adding extra Al2O3.