Statistical analysis of chemical-technological research on copper baptismal cross collection from Ilimsk fortress

Purpose. On the basis of the X-ray fluorescence (XRF) analysis applied to the collection of copper baptismal crosses from Ilimsk fortress, the author identifies the alloys used and finds correlations between the features of the alloy and the type of the item made of such an alloy. Methods of mathematical statistics are used to classify alloys on the basis of the features of their ligature components. Results. The author compiles a database of the ligature composition of 196 samples analyzed and provides the data, which contain the results of XRF analysis, as a summary table based on the academician V. I. Molodin’s classification. The article is illustrated with bar charts and graphs showing the number of components and their distribution by type. All the items of the collection are systematized based on the information about the alloy components and the item type. The results of the analysis were processed using the statistical program SPSS Statistik. Our analysis shows that the main component of the items is copper, which is determined in 192 items. There are some items found containing no copper or a very small amount of it (less than 7.97 %). The latter group includes six types of crosses: the sixth type (5 items), the second, seventh and fourth types (2 items in each type), and the ninth and eleventh types (1 item in each). Crosses of the sixth and seventh types were made almost entirely of lead (98.63 and 81.42 % respectively) while others were made of a tin-zinc alloy. Conclusions. Statistical analysis showed that the most representative group of the items were made of brass, a composition of copper and zinc (50 items). The second biggest group included items made of copper-tin-plumbum alloy (35 items). Then comes the group made of a multi-component alloy including all four of the alloying constituents (34 items). It is followed by a group of 28 items made of copper-zinc-plumbum alloy. There is also a group of items made of copperzinc-tin, and 17 items contain silver. The differences recorded in each type of the alloys speak in favor of certain recipes for manufacturing products, which were connected with the shape of the items manufactured. Alloy components changed the technological properties of the alloy giving them flexibility and fluidity, and the use of certain dopants changed the color of the alloy helping to imitate some noble metals, particularly silver. Our results of analyzing the alloys used in the items made it possible to identify the chronological frameworks of manufacturing baptismal crosses. We date them the XVIII-XIX centuries.