Diopside is widely recognized as a raw material for glass-ceramic, due to its relatively low melting point and the low viscosity of the melt. The use of diopside-rich rock, replacing up to 20 wt% of the potassic feldspar added to ceramic bodies improves their technical features, reducing water absorption while maintaining constant the drying linear retraction and increasing the flexural resistance, for porcelains produced at low temperature. The use of diopside, not only on ceramic, was investigated in the past by several authors [1][2][3][4][5][6]. In Brazil, however, studies of technological application of diopside-rich rock are still restricted [7][8][9].Diopside-rich rock used in the present study was collected in Castro Alves district (Bahia, northeastern Brazil). The geological setting of the area refers to the S. Francisco Craton, with metamorphic rocks of granulite to high amphibolite facies that belong to the Jequié and Caraíba Complexes. The Caraíba Complex has lense-shaped bodies of diopside-rich rock, which may reach up to 700 m in length and 200 m in width, usually aligned in the NW-SE direction. These diopside-rich rocks are deformed and cut by granites and pegmatites, with intrusive breccias and veins. Diopsiderich rock is mainly composed by diopside, with minor amounts of tremolite, feldspar, quartz, carbonates, titanite, garnet, epidote and tourmaline -nevertheless, the wholerock chemical composition is close to the stoichiometric composition of diopside (MgCaSi 2 O 6 ). dias@usp.br, gajszabo@usp.b, motta.jf@gmail.com, marsis@ipt.br Abstract White ceramics were produced with raw mixtures prepared with varying proportions of diopside-rich rock (0 to 20 wt.%) and potassic feldspar (40 to 20 wt.%), and fixed proportions of kaolinite (40 wt.%) and quartz (20 wt.%), fired in a temperature range from 1170 to 1210 o C. The phases identified in the experimental ceramics were quartz, anorthite, mullite and glass, and their relative mass proportions were determined by X-ray diffraction (Rietveld method). The addition of diopside as a partial substitute for potassic feldspar causes the formation of a calcium silicate, analogous of the natural anorthite (CaSi 2 Al 2 O 8 ) in the ceramics, with proportional reduction in its glass and mullite contents. Water absorption and porosity of the ceramic bodies clearly decrease with increasing firing temperature, while the effect of the raw mixture composition on the physical and mechanical properties of the ceramics is less evident. Diopside-rich rock has low iron content (1.5 wt.% Fe 2 O 3 ) and, therefore, promotes white burning.