History of Technology in India, Vol. I: From Antiquity to c. 1200 A.D. v1.c39.s2.t3.16

v1.c39.s2.t3.16

Lastly, the Northern Black Polished Ware or NBPW also showed under an electron microscope opaque crystals of magnetite (produced similarly) in a background of amorphous glass-like matrix which assayed 11-13 p.c. Na2O and 2-4 p.c. CaO. For producing this glassy glaze, sājjimāṭṭi or reh, the alkaline, natural efflorescence, profusely found in the Ganga valley, chiefly in the mid-eastern and eastern Uttar Pradesh and Bihar, was used (Hegde, 1987). This sājjimāṭṭi assays 20-40 p.c. Na2O, 50-70 p.c. silica and 5-10 p.c. lime. Availability and use of sājjimāṭṭi enabled the PGW people to produce not only the famous glassy glaze in NBPW but also the soda-lime glass (Hegde, 1987; Tripathi, 1976; Roy, 1986; Sen and Chaudhuri 1985). Very significantly Atranjikhēra and Hastinapura produced the earliest samples of glass in India. The Harappan people could produce faience but not glass.