"This research project focuses on the Ghaggar plains, which occupies the north-eastern corner of the Indus society, in order to understand the temporal change of craft production through time from the Indus urban period to the post-urban period in this region. As a part of the project, faience objects have been subjected to a series of scientific analyses to identify their raw materials and production technology" (p. 1) write the authors of their work which primarily covers sites in Rajasthan and Haryana like Rakigarhi, Bhagwanpura, Bhiwani, Tohana, Anupgarh and Farmana. "Based on these evidence, it can be stated that the faience in the Ghaggar plains developed in the urban phase and continued into the post-urban phase and that the dominant objects are ornaments like beads and bangles, although other objects, such as vessels, are also represented in a few number. Regarding their colours, green or blue colours are predominant. For shapes, there is a strong similarity among specimens of the urban phase and the post-urban phase. The incised decorations are prominent on bangles" (p. 7).
One of the questions they seek to answer is whether this extensive craft production was an indigenous or imported tradition. Because no kilns for firing faience have (yet) been found in Indus excavations, and faience production requires high heat sources, the authors can only compare the objects to Egyptian faience production of the same period (the Ghaggar objects are similar formally to those found at Harappa). They conclude, tentatively, that there are a number of differences with Egyptian faience production in chemical composition, glazes and firing techniques which suggest local production. Evidence from Mithathal, excavated after the first version of this paper was written, and which has offered a more extensive chronology of faience production in the region given the care with which stratigraphic data was preserved, also suggest that "it appears that faience objects increased in the late phase of the urban phase. Especially, the topmost level that can be dated to 2000 - 1900 cal BC yields the most numerous number of faience objects" (p. 20).
In short, a lot more work needs to be done, but tackling some of the mysteries of the sophisticated craft technologies employed by Indus artisans are likely to yield many exciting results to the kind of X-ray fluorescence and powder analysis used by the investigators.
Representative specimens of faience objects in the Ghaggar plains (surface collection by V. Dangi)