The kaolin clay occurring at Djebel Debbar has been used as an important plastic raw material for the production of pottery in Algeria. Its chemical and mineralogical properties, and their influences on slip conditioning, pottery shaping and fired properties were investigated. The principal constituent of the clay was halloysite (10 Å) with a tubular morphology and particle distribution rich in colloidal size particles. In the kaolin deposit, high-grade part with SiO2/Al2O3 ratios in the range from 1.90 to 2.00 was studded with variety size of blocks in the low grade region. The amount of the high-grade ores occupy about 10 to 20% of the output, and the rest are lowgrade ores. They are dark-colored due to the coexisting manganese compounds, calcite, alunite, etc.. The main contaminants are lithiophorite with relatively high Li content, and fine aggregates of colloidal particles. The impurities of Mn amounted to several % as MnO2 can be removed easily with reducing agent such as sodium dithionite. The slurry of the body system containing the halloysite clay was rather difficult to disperse by the conventional deflocculants, because of much amount of electrolytes from the raw materials and the hard water used. Furthermore, the colloidal particles in the system are in significant amounts resulting in very large viscosity unusable to the shaping, or requiring much water content. Surface properties of the very fine halloysite particles were of benefit to the dry strength and to the rheological feature for plastic formation of the body. The slip rendered the rheological properties available to both slip casting and jiggering by lowering the clay content to 12% and by using barium carbonate, sodium salt of humic acid and sodium silicate as defloccurants. Barium precipitated sulfuric ions and humic acid played an important role, in forming complexes with the polyvalent metal ions and to disperse manganese particles homogenously into the whole body. The clay containing the manganese compounds lowered the vitrification temperature and water-absorption of the fired body.
