An Encyclopaedia of Indian Archaeology v1.c21.s8: 16.8 Glass
An Encyclopaedia of Indian Archaeology v1.c21.s8
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16.8 Glass
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Objects of glass have been found in association with the PGW [11.14] at AHICCHATRĀ, HASTINĀPURA, ROPAR, ALAMGIRPUR and ŚRĀVASTĪ, the objects being respectively: a black opaque bead; a bead and two fragments of light brown and black bangles; a bangle; beads; and green bangles and beads. The Chalcolithic [4.14.8] levels of MASKI have yielded four beads including one of blue opaque glass.
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Glass objects are prolific in later times, including the Megalithic [4.17], e.g. MASKI. They mostly consist of beads, bangles of round, triangular or rectangular sections, bracelets, finger rings, discs and occasionally vessels (including Roman ones from ARIKAMEDU), cylindrical weights and discs. Of technological interest are the bichrome and polychrome objects found in the late historical period, gold-foiled objects with one colour in the core and another at the exterior, objects produced of cane glass and moulded glass and glass frit (e.g. at AHICCHATRĀ). Polychrome specimens show a remarkable skill in glass-moulding and annealing.
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Our knowledge of the nature and composition of Indian glass is based on the chemical analysis of some 60 specimens. The more significant of them are as follows.
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HASTINĀPURA, PGW level, two specimens: the first, a brownish bangle, an ordinary soda-lime silicate containing some oxide of iron accounting for its colour, with a low alumina and silica content and being soft suitable for bangle-making; and the second a black glass bangle, also of soda-lime silicate, with a low proportion of silica and alumina, therefore soft and easy to work, the black colour being due to the presence of iron oxide. After fabrication the objects were probably subjected to careful annealing. When excavated the objects were fresh and free from decomposition and devitrification. The specific gravity lies between 2·55 and 2·6; the hardness is about 6.
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RAJGHAT⁴, five specimens, all early historical: RG1, opaque reddish-brown bead; RG2, translucent pale blue bead; RG3, transparent olive-green bead; RG4, translucent bluish-green bead; and RG5, translucent black bead. Four specimens represent soda-lime silicates and the fifth soda-potash-lime silicate. The sesquioxides amount to about 12% in three specimens, while the other two contain only 4·6%. Lime-magnesia concentration ranges between 4·51 and 6·79% in three specimens and 9·02 to 10·00% in the other two. The specimens with low sesquioxides are found to contain a high lime-magnesia content; thus where the former is high the latter is low. The tinctorial agents are oxides of iron and copper; the colouring agent of the opaque red glass is cuprous oxide. The specific gravity ranges from 2·31 to 2·49.
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MASKI, five specimens: MK4 and MK5, Pd II, and MK1 to MK3, Pd III. MK1 is liver-red opaque weathered disc; MK2 dark brown moulded weathered glass; MK3 black weathered glass; MK4 bottle-green transparent bangle fragment; and MK5 purple transparent moulded bangle fragment. The specimens represent soda-lime silicate glass. The tinctorial agents are oxides of iron, copper, manganese and nickel. The liver-red colour is due to red oxide of copper, the green to oxide of iron (ferrous), the yellow to ferric oxide and the purple to manganese oxide. The specific gravity respectively is 2·34, 2·47, 2·21, 2·14 and 2·70.
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KOPIA, three specimens, all early historical: KP1 is a colourless bead: KP2 black bead; KP3 pale yellow strip. KP1 is colourless due to the low proportion of ferric iron (2·50%) and the presence of manganese (0·1 manganese oxide). The black colour of KP2 is due to the high iron content and the pale yellow colour of KP3 of the low proportion of iron and a low concentration (0·08%) of manganese, which was evidently not sufficient to decolourize the glass completely. All the specimens are characterized by a low content of lime and magnesia and a high content of iron oxide and alumina. The specific gravity ranges from 2·51 to 2·53.
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AHICCHATRĀ, two specimens: AC1, blue glass and AC2 green glass, both of the 1st century. The specimens represent soda-lime-silicate glass and are characterized by a high proportion of lime and magnesia and a low content of the sesquioxides. The presence of lead (PbO) in AC2 is significant as the use of lead in glass-making in the 1st century is very rare. The blue colour is due to copper oxide and the green to the combined effect of copper and lead oxides.
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ARIKAMEDU, four specimens, all 1st-2nd century: AK1 is deep violet glass; AK2 bluish-violet glass; AK3 dull blue opaque bead; and AK4 deep red opaque glass. They represent potash-lime silicates, characterized by a high silica, a low lime-magnesia and iron oxide alumina contents. Manganese is responsible for the violet colour and the blue colour is due to the combined effect of ferrous iron and manganese. The specific gravity ranges between 2·51 and 2·63.
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NĀLANDĀ, four specimens, all late historical. NL1 is a fragment of sky-blue glass; NL2 rectangular object of green glass; NL3 bead of opaque red glass; and NL4 blue glass. The red colour of NL3 is due to the combined effect of cuprous and ferrous oxides. The tinctorial agent of the blue glass is cuprous oxide and iron oxide is responsible for the green colour.
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NĀSIK, two specimens both early historical: NS1 is bottle-green glass and NS2 black glass, both 4th century B.C., respectively soda-lime and soda-potash-lime silicate. The colour of NS1 is due to iron oxide. The specific gravity is respectively 2·59 and 2·52 and hardness 5 to 6 and 5.
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The chemical compositions (per cent) of the above specimens are as follows.
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SiO₂—in RG1 65·01, RG2 68·05, RG3 67·07, RG4 70·09, RG5 64·68; MS1 72·32, MS2 71·05, MS3 62·00, MS4 73·23, MS5 59·42; KP1 63·30, KP2 62·24, KP3 70·30; AC1 61·49, AC2 59·56; AK1 73·62, AK2 72·49, AK3 73·06, AK4 64·81; NL1 61·21, NL2 70·74, NL3 61·50, NL4 63·44; NS1 65·28, NS2 55·55.
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Al₂O₃—in RG1 2·28, RG2 2·76, RG3 9·95, RG4 3·34, RG5 7·89; MS1 2·57, MS2 2·33, MS3 3·58, MS4 5·07, MS5 11·48; KP1 7·09; KP2 8·46, KP3 5·30; AC1 0·66, AC2 0·05; AK1 1·38, AK2 1·12, AK3 1·90, AK4 1·20; NL1 1·81, NL2 6·13, NL3 Fe₂O₃ 9·82, NL4 (with Fe₂O₃) 6·90; NS1 5·75, NS2 9·89.
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Fe₂O₃—in RG1 9·96, RG2 1·84, RG3 2·59, RG4 1·26, RG5 4·20; KP1 2·50, KP2 7·20, KP3 1·20; AC1 5·29, AC2 5·40; AK1 3·84, AK2 6·50, AK3 1·10, AK4 3·41; NL1 1·60, NL2 1·54; NS1 4·78, NS2 3·06.
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FeO—in AK3 2·00, NL3 7·01.
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TiO₂—in KP1 1·10, KP2 0·51, KP3 trace; AK4 0·31.
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NiO—in RG1 0·15; MS1 0·27.
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PbO—in AC2 4·23; AK1 0·07, AK2 0·07.
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MnO—in MS1 3·43, MS2 and MS3 trace; KP1 0·10, KP2 0·02, KP3 0·08; AC2 0·06; AK1 5·01, AK2 1·99 AK3 0·40; NL2 and NL4 trace; NS1 1·73, NS2 trace.
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CuO—in RG2 2·40, RG4 1·13; MS5 2·69; AC1 2·39, AC2 1·82; AK4 0·72; NL4 1·13.
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Cu₂O—in RG1 5·27; AK4 1·33; NL1 0·75, Nl3 0·49.
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CaO—in RG1 4·08, RG2 8·04, RG3 6·35, RG4 8·90, RG5 5·42; MS1 2·71, MS2 5·65, MS3 5·48, MS4 9·78, MS5 5·61; KP1 3·64, KP2 3·13, KP3 2·38; AC1 6·60, AC2 6·54; AK1 1·96, AK2 2·94, AK3 3·90, AK4 4·81; NL1 8·15, NL2 2·11, NL3 5·20, NL4 8·00; NS1 11·88, NS2 5·59.
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MgO—in RG1 0·49, RG2 0·98, RG3 0·44, RG4 1·10, RG5 0·86; MS1 and MS2 trace, MS3 3·11, MS4 2·34, MS5 3·13; KP1 1·85, KP2 1·55, KP3 1·20; AC1 4·61, AC2 4·34; AK1 0·30; AK2 0·68, AK3 1·40, AK4 2·35; NL1 3·83, NL2 0·26, NL3 0·06, NL4 4·14; NS1 1·48, NS2 2·93. P₂O₅—in AC1 1·94, AC2 1·36; AK4 5·00. SO₃—in AK4 0·10. Na₂O—in RG1 13·05 (with K₂O by difference), RG2 16·03, RG3 13·81, RG4 5·25, RG5 17·54; MS1 16·62, MS2 20·29, MS3 20·66, MS4 9·58, MS5 17·67; KP1 20·52, KP2 16·70, KP3 19·31; AC1 15·32, AC2 14·19; AK1 1·30, AK2 0·20, AK3 2·10, AK4 11·35; NL1 18·25, NL2 15·80, NL3 15·69; NS1 7·88, NS2 16·26. K₂O—in RG2 0·62, RG3 0·36, RG4 9·74, RG5 0·30; AC1 2·67, AC2 2·41; AK1 12·78, AK2 14·14, AK3 13·40, AK4 4·32 (SnO₂O); NL1 4·98, NL2 2·94, NL3 15·92 with K₂O (by difference), NL4 1·54; NS1 1·06, NS2 16·12. H₂O⁺—in MS1 0·98, MS3 1·46; NS1 0·18, NS2 0·56. Nil in cases where not specified.
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Spectrochemical analysis of five specimens from TRIPURĪ has shown a lump of transparent bluish-green glass (300 to 100 B C.) to be a soda-lime silicate containing lead and copper which account for the colour. A blue tube-glass bead datable to c. 100 B.C. to A.D. 200 has also been found to be of soda-lime silicate, the colour being due to copper. Of particular significance are the other three specimens—a green bead (100 B.C. to A.D 200) and two blue beads (A.D. 200-400), which have been found to contain 3 to 5% barium and a high proportion of lead. Barium has not been found in any other Indian glass specimen.
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Lal, B.B., 1952, in *AI*, 8, pp. 17-27. For sites see respective entries in vol II—B.B. LAL (Dr)