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The effect on ceramic products of firing conditions in the presence of abundant organic matter is assessed here experimentally by reproducing two ancient firing techniques: pit firing, characterised by a high heating rate and short residence time in a reducing atmosphere; kiln firing, with a low heating rate and long residence time in an oxidising atmosphere. As expected, pit firing conditions produced uniformly reduced ceramics, and gehlenite, diopside and spinel occurred at suitable temperatures (above 900 °C). Interestingly, in kiln firing conditions, sandwich structures formed in the ceramics, in which mineral assemblages and Fe oxidation state turned out to be different in the black core with respect to the margin. Spinel, cordierite and metallic Fe formed in the core, whereas hematite and spinel, in addition to gehlenite and diopside, crystallised in the margin at suitable temperatures (above 800 °C). Therefore …