PETROGRAPHIC METHODS IN THE STUDY OF HALLSTATT GLASS BEAD MANUFACTURING TECHNIQUES (Badania techniki wyrobu paciorków szklanych okresu halsztackiego metodami petrograficznymi)
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Studies of techniques used for the manufacture of glass beads discovered at Lusatian sites are not much advanced. To date, it has been established solely that some of the beads from several sites were produced by the winding technique. Some beads from Wicina underwent additional treatment. Not all Hallstatt period beads bear evidence of the manufacturing technique. The glass is usually poorly transparent or of such good quality that no faults can be seen in the glass mass to suggest the character of these techniques. The forming in the case of these beads is commendable for its quality and it is clear that additional treatment had in most cases removed all traces of technical processes of manufacture. An effort was made to see whether the petrographic method can be of use in determining the production techniques. The method calls for examining thin sections cut from a given object in order to observe its internal structure under a microscope. Five beads (of HaD period) from Wicina stronghold were examiined. Three of these were of clearly transparent and the other two of poorly transparent glass. Three had the canal opening surfaces smoothened. Eight thin sections were cut: a transverse one, positioned perpendicularly to the long axis of the canal opening, for all five beads, and another longitudinal one, parallel to this axis, for three of them. The thin sections were then examined under a polarizing microscope. Nothing but a few small, mostly round gas bubbles could be observed in the sections of bead no. 5. Also the transverse section of bead no.19 revealed just single round gas bubbles. As for bead no. 29, both thin sections demonstrated many round gas bubbles of different size. The horizontal section also showed concentric trails around the canal opening, telltale signs of the winding technique used in its production. Bead no. 45 was made by a similar technique; the transverse section displayed many round gas bubbles accompanied by a few that were slightly ellipsoid in shape, arranged perpendicularly or at an oblique angle toward the canal axis. Both sections of bead no. 61 presented primarily very numerous round gas bubbles of different size. A magnified view of the same section revealed fine trails laid concentrically around the canal opening, as well as single slightly ellipsoid bubbles arranged obliquely, again proof of the winding technique in operation. In the case of this bead, the flat canal opening surfaces should be noted, evidently cut off and smoothened by the beadmaker. The results of the examination of petrographic thin sections of five glass beads from the Wicina have demonstrated the usefulness of the method in determining bead-making techniques attributed to the Halstatt period. In three cases, innumerous ellipsoid gas bubbles and trails betrayed the use of a winding technique - winding the glass mass on a rod - for the manufacture. In the other two cases, there were no features that could be interpreted but the glass of these beads, clearly transparent and greenish in color, was of very high quality (well melted and cleared) and the objects had undergone additional treatment, like cutting off, smoothening and grinding away any surface evidence of manufacturing technique. 13 Figures, 1 Table.
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