Their matrix is fine calcareous and slightly ferruginous marl with some dolomitic and rare quartz silt. The non-plastic inclusions comprise not more than five percent of the sherds’ volumes, and are predominantly euhedral rhomboid dolomite crystals with sizes ranging between 0.1 and 0.3 mm. The dolomite is partly decomposed to calcite as a result of firing (decomposition occurs at 500ºC when fired in an oxidized atmosphere). Besides the dolomite, there are rare 0.2–0.8 mm lumps of pure ferruginous or silty ferruginous shale, quartz siltstone with calcareous cement, and micritic limestone. Sporadic are circular (0.2–0.3 mm in diameter) and elongated (0.5 × 1.2 mm) cavities with gray aureoles, originated from some fine organic matter and vanished during firing.

The optical properties of the clay and calcium carbonate minerals, and the presence of the charred aureoles after organic
inclusions and/or grayish core, allows us to estimate a firing temperature of 700ºC.