MUD VOLCANOS OF TRINIDAD - NATURE MINED SOURCES OF RAW-MATERIAL FOR CERAMICS

As a potential raw material for ceramics manufacture, the effluent fro m the Devil's Woodyard mud volcano of central Trinidad has been invest igated. Chemically, the material was found to contain 2% organic matte r and 54, 18, and 6% SiO2, Al2O3, and FeO3 respectively. Loss on ignit ion at 1000 degrees C amounted to 13.2% and the soluble sulphate and p hosphate contents were 0.6 and 0.15% respectively. Mineralogically by X-ray diffractometry and differential thermal analysis, the high plast icity effluent was found to be essentially a kaolinitic clay. Some qua rtz, mica, potash feldspar, and calcite were also detected. Rectangula r test bars fired at 800-1100 degrees C resulted in the 'black core' p henomenon and bloating at and above 1000 degrees C. However, bars fire d for 3 and 4 h at 800-900 degrees C, where no bloating occurred, exhi bited modulus of rupture and fracture toughness values comparable with , or superior to, those exhibited by other Trinidad clays fired in exc ess of 1000 degrees C for 3 h. The associated linear firing shrinkage was less than 3%.