This report details the results of a research program focused on mineralogical and physico-chemical behavior of several natural clays during firing. The experimental program was designed to shed light on incised gray pottery from Hili in the Emirate of Abu Dhabi pertaining to the 3rd Millennium B.C. The project focused on transformation of carbonates during firing, on firing changes in other minerals, on the determinants of fired color, and on source attribution by chemical characterization. Evolution of carbonates (calcite, aragonite, dolomite) was found to vary according to initial granulometry, mineralogical composition, firing atmosphere, and firing speed. This complicates temperature estimation based on changes observed in calcite. Other minerals, such as green hornblendes and olivines, may be at least as reliable as temperature indicators as calcite. The color of ceramics is likewise a complex result of composition and firing effects. Source attribution by major element analysis is found to be highly suspect. The Bronze Age incised gray ceramics from the Hili area were found to have been made from local clays; their color is achieved by reduction of iron oxide at the end of the firing at temperatures below 800 degrees C; the exact firing temperature of the Hili pottery probably was between 704 degrees C and 768 degrees C.