摘要：Nearly 200 glass beads found in Sarmatian (2nd
-4th
cent. AD) and Avar (6th
-8th
cent. AD ) graves in recent
Hungary were subjected to instrumental analysis. The Sarmatian beads are monochrome, the Avar beads are
often decorated. The textures, inclusions, precipitations, colouring and modifying components, inhomogeneities
of glasses with different colours were investigated, and exact quantitative analyses were done by electron
microprobe and X-ray diffraction. The beads and the determined compositions of the glasses are listed in
Appendix. A review of the literature of ancient and early medieval glass making and colouring is given in order
to understand the obtained results.
The coloured glass beads not only follow the fashion but reflect changes in technology, too. Blue glass was
coloured in Sarmatian time presumably by cobalt with antimony added, in Avar age mainly by bivalent copper
combined by lead. The green colour was produced mainly by copper in both ages. The red glass was coloured by
elementary copper precipitations, produced by reduction of bivalent copper oxide. In Avar age iron was used as
inner reducing agent, proved by the microtexture and chemical compositions; in Sarmatian age another
technology was used, its traces we could not detect. Orange glass – coloured by reduced copper and tin- and
lead-oxide – was made only in Sarmatian age. The red and orange beads found in Sarmatian graves are made of
„ash” type glasses, glass beads of other colours were mainly made of „soda” type glasses from both ages as
well as red Avar glasses. Yellow glass was found in Avar graves only, it is rich in lead and has been coloured by
PbSn1-xSixO3 grains. White glass obtained its colour from antimony-oxide in Sarmatian age and from tin and
lead-oxide in Avar age. The texture and compositions of the black glasses are diverse, the majority of Avar black
beads have high iron contents.
The differences in material – in texture and in chemistry – made it possible to classify in cases of uncertain
graves, and indicated repeated use of a few glass beads.
Excluding Sarmatian red and orange beads, the majority of the glasses belong to “soda” type glasses, but “ash”
type glasses also appear; both types have been coloured similarly. The simultaneous occurrence of the two types
indicates that the production and processing – colouring and bead production – were done in different places,
and the processing workshops worked with rough glasses originating sometimes from distant places from each
other.
In cases of Early Avar beads the decorations were compared with monochrome beads and with “bases” of
decorated beads of the same colours. We found that the textures were similar, but small differences appeared in
compositions. Unequivocal differences, proved by statistical t-probe were found in iron contents of the red
glasses and in lead contents of every colours. These are interpreted as intentional differences, preventing
unwanted changes in the colour, or modifying the colour, or influencing the softening temperature of the glass.
