Ceramics molding masses of the Andronovo (Fedorovo) culture burial ground Tartas-1: instrumental examination results

The Tartas-1 Andronovo (Fedorovo) culture burial ground collection has been partially introduced into scientific circulation: the characteristics of morphological and ornamental traditions have been published. Methods of extracting technological information were used to analyze the molding mix of 271 vessels. The results of petrographic analysis provided the qualitative and quantitative relation between the components of a molding mass; X-ray phase analysis recorded the presence of all crystalline phases. Derivative gravimetry methods determined the presence of clay and carbonate minerals, and the degree of thermal decomposition of clay minerals during firing in the process of ancient production, which made it possible to record the quality of clay products. Three recipes for molding masses have been recorded: clay raw materials + chamotte (25); clay raw materials + chamotte + organic matter (75 %); and clay raw materials + chamotte + crushed rock + organic matter (3 samples). Loams with montmorillonite-hydromica or hydromica clay part were used as raw materials for the production of dishes. The use of at least two sources was noted, one of them with the inclusion of calcites. Clay raw materials (low, medium, and strongly ferruginous, medium sandy (1-30 %)) were used in a state of natural moisture (signs of drying and crushing are not recorded). Chamotte was a mineral additive in the molding mix and it was recorded in all samples at different concentrations (1: 20; 1: 10; 1: 7; 1: 5; 1: 4). The dependence of its amount on the amount of sand in clay is noted. Organic matter was detected in 75 % samples. Three vessels made of the molding mass according to the recipe: clay raw materials + chamotte + crushed rock + organic matter, were imported. Most of the items are fired in a reducing environment and a few in an oxidizing environment. Samples with calcite have a goodfiring quality, the rest are more diverse in terms of the preservation of the clay component in the molding mass.