Title:	Fragment of wall painting depicting a grazing cow
Material:	loess plaster base (clay and chopped straw), gypsum primer, mineral pigments
Front side or imprint:	imprint
Dimensions:	22 × 18 cm
Site of discovery:	the large columned hall (the room 15) of the palace of Argishti I at Erebuni
Research laboratory that performed the study:	Laboratory of chemical and technological research of the State Research Institute of Restoration (GosNIIR)

The study of the mural fragment depicting a grazing cow from Erebuni managed to conduct a stratigraphic analysis of paint layers on the basis of the analysis of sample No. 17. This fragment of the wall painting consists of four layers. The first layer is formed by the plaster base, followed by a second layer of blue paint layer, the third consists of a white plaster primer and the final fourth layer is represented by a semi-transparent film of restoration glue.

In the laboratory, two additional samples of the plaster base were taken from the mural fragment U-409. In both cases, the samples are sections of the plaster base with traces of the paint layer. The element analysis of the chemical composition of the first sample No. 18 (Fig. 1) has produced the following results: calcite (a small amount), quartz, mica, aluminosilicates (mica, etc.) and iron hydroxides (Table 1).

Table 1. The chemical composition of the sample of the plaster base of the mural fragment U-409, sample No. 18.

Oxides	MgO	Al2O3	SiO2	P2O5	SO2	Cl	K2O	CaO	TiO2	Сr2O3	MnO	Fe2O3
1	2	3	4	5	6	7	8	9	10	11	12	13
Composition, mass. %	2,90	14,20	51,00	0,13	0,09	0,36	5,10	12,40	1,06	0,05	0,24	12,20
Oxides	CoO	CuO	ZnO	BaO
14	15	16	17	18
Composition, mass. %	0,13	0,05	0,04	0,125

The analysis of the second sample of plaster primer with the remains of the paint layer (sample No. 19) indicates that the chemical composition of this section of the wall painting (Table 2) almost completely coincides with the results of the analysis of the previous sample No. 18 (Fig. 2).

Table 2. The chemical composition of the sample of the plaster base with the paint layer of the mural fragment U-409, sample No. 19.

Oxides	MgO	Al2O3	SiO2	P2O5	SO2	Cl	K2O	CaO	TiO2	Сr2O3	MnO	Fe2O3
1	2	3	4	5	6	7	8	9	10	11	12	13
Composition, mass. %	3,245	13,90	55,80	0,12	0,24	0,43	4,40	9,95	0,86	0,06	0,20	10,30
Oxides	CoO	CuO	ZnO	BaO
14	15	16	17	18
Composition, mass. %	0,12	0,05	0,028	0,15

The plaster base of the mural fragment U-409 consists of loess deposits with the plant filler in the form of chopped straw, which has been preserved as impressions on the plaster. However, unlike most of the other discovered wall paintings from Erebuni, the fragment U-409 is a rare example of the ancient original primer.