History of Technology in India, Vol. I: From Antiquity to c. 1200 A.D. v1.c17.s2.t2.4

v1.c17.s2.t2.4

Recently, Hegde et al (1982) have examined the Harappan microbeads made of steatite and obtained from Zekda, located in Banaskantha district in the northern part of the Gujarat State. The raw material was aluminium-containing talcose steatite available in Ambaji near Zekda. The X-ray diffraction patterns in the finished beads revealed the presence of silica in the form of cristobalite and anhydrous magnesium silicate in the form of enstatite. When talc is heated around 900°C it loses its water of crystallisation, forms cristobalite and enstatite, and improves its hardness from one to seven on the Moh scale.