The stone beads appear in archaeological record since the Upper Palaeolithic times in India. The emergence of exotic raw materials and a drilling technology to perforate the hard stones can be seen from Neolithic times at Mehrgarh (Pakistan). The exotic raw materials like turquoise, carnelian, steatite, marine shells from Mehrgarh from 7th millennium BCE indicates a long distance trade network established between cultures in different parts of South Asia.
The evidence for sophistication in bead drilling technologiesfrom Chalcolithic period onwards could be seen at several sites like Mehrgarh, Harappa, Dholavira, to name a few. Different stones like chert and jasper were employed to perforate the harder stones of agate-carnelian, belonging to quartz family. With the advent of Harappan Civilization (circa 2600 – 1900 BCE), a new material for perforating the harder stones was introduced, which has been tentatively named as ‘ernestite’ after the famous archaeologist, Ernest Mackay. The geological provenance of this hard stone is yet to be ascertained and hence the use of ‘ernestite’ has gained currency among the archaeologists.
Ernestite is present in more numbers from the sites ofGujarat in general and Dholavira in particular. So far, 1588 drill bits of ernestite has been documented from Dholavira and it is the largest collection so far from any Harappan site.
Various drilling techniques of stone beads have been identified by scholars like Jonathan Mark Kenoyer, Massimo Vidale and others. They are, pecking, stepped drilling, copper tubular drilling, to name prominent ones. Often, combination of these techniques was also noticed. The stepped drilling, mostly with the aid of ernestite drills was employed to manufacture a hallmark anddistinct variety of stone beads in the form of ‘long barrel cylindrical, which in turn formed part of a multi-stringed waist band, only three examples of such type have been found so far, one each from Mohenjo-daro, Harappa and Allahdino (all in Pakistan).
Research at IIT Gandhinagar
Jonathan Mark Kenoyer has pioneered the technique of analyzing bead-drilling technology with silicone impressions of perforations. The silicone impressions from the Harappan sites of Karanpura (Rajasthan), Dholavira (Gujarat), late Harappan site of Sanauli (Uttar Pradesh) and Chalcolithic site of Daimabad (Maharashtra) were available for study.
The bead impressions from Karanpura were analysed with the SEM at IIT Gandhinagar. On analysis, it has been found out that at least three different types of drilling mechanisms were involved in the manufacture of Karanpura beads, namely pecking on both sides, pecking on one end and drilling on other and stepped drilling. The bead impressions also indicate polished surfaces, which is an indicator of drilling by ernestite drill bits.
A nodule of ernestite found from the surface from Bhagatrav, district Bharuch, Gujarat was also analysed with XRD. The analysis indicated peaks of quartz, sillimanite and mullite confirming to the spectra of similar stones from Harappa and Dholavira. The bead impressions from other sites are being analysed which may add new facets to the understanding of bead drilling technology of Harappans.