Late antique glass vessels and production indicators from the town of Herdonia (Foggia, Italy): new data on CaO-rich/weak HIMT glass

In the framework of the archaeometric research on Apulian Late Antique glass, a collection of 24 glass vessels (third to seventh centuries ad) and production indicators found at Herdonia (Foggia, Italy) was examined, by means of SEM-EDS, EMPA, ICP-MS and LA-ICP-MS. A fragment of crucible was further investigated by SEM-EDS and EMPA. The results obtained were discussed together with another glass collection from Herdonia previously investigated. The full set of 48 samples was made of siliceous sands mixed with plant ashes (two samples: a dark green slab and a colourless beaker/lamp) or natron (all the other 46 samples). The latter were assigned to the following compositional groups: HIMT, Levantine 1, RNCBGY1, RNCBGY2, RC/LAC-Sb, intermediate HIMT/RNCBGY1, intermediate RNCBGY1/HIMT, intermediate Levantine/RNCBGY2 and two other groups, the CaO-rich HIMT and the CaO-rich/Na2O poor HIMT, which showed a prevailing Adriatic distribution and a close similarity to the weak HIMT glass group. Most Herdonia samples were similar to the HIMT productions, and thus of likely Egyptian origin, while a smaller number of samples referred to the Levantine productions.