Minerals and Metals in Ancient India v1.c22.s2.12

v1.c22.s2.12

Table 14.3 present the chemical composition of glasses found in Taxila, Rājghāṭ and Kopia. It is seen that these were basically soda-lime glasses. In Taxila, CuO was added to make blue bangle (0.44%), green blue tile (0.2-0.6), and turquoise blue powder (3.6%); about 5.08 per cent and 2.42 per cent Sb₂O₃ were present in white opaque glass and turquoise blue powder respectively. A red opaque glass assayed 37.1 per cent SiO₂, 10.3 Na₂O. 6.5 CaO, 0.9 K₂O, 0.7 MgO, 3.2 Al₂O₃/Fe₂O₃, 0.1 MnO and colouring agents: 7.2 per cent Cu₂O and 34.9 per cent PbO. Blackness of some Indian glasses is due to iron and manganese oxide. Cu, Cu₂O and CuO are common ingredients in many coloured glasses of ancient India. Some of the other colour-producing oxides used in Indian glasses are: PbO (Taxila, Tripurī, Ter, Ahicchatra), SnO₂ (Kauśāmbi, Arikamedu), Sb₂O₃ (Taxila), BaO (Tripurī), P₂O₅ (Kauśāmbi, Ahicchatra, Arikamedu) etc.