Mahala, M. K.M. K.MahalaRay, Jyotiranjan S.Jyotiranjan S.RayKanungo, A. K.A. K.KanungoSree Bhuvan, G. N.S.G. N.S.Sree BhuvanChatterjee, A.A.ChatterjeeGeorge, B. G.B. G.GeorgeSorcar, N.N.SorcarRawat, Y. S.Y. S.RawatKharakwal, J. S.J. S.KharakwalRajesh, S. V.S. V.Rajesh2025-12-102025-12-102025-12-0110.1038/s40494-025-02147-22-s2.0-105023439559http://repository.iitgn.ac.in/handle/IITG2025/33609Advancements in stone bead technology, particularly in drilling techniques, emerged during the Indus Valley (Harappan) civilization. Long-constricted cylindrical drill bits, made from a unique stone called Ernestite, were a distinctive feature of this culture. The origin of Ernestite remains uncertain, as it has no known natural analog and its synthesis process is poorly understood. This study presents a mineralogical and geochemical investigation of Ernestite stones and drill bits from multiple Harappan and contemporaneous sites in Gujarat, India, to uncover their origin. The ⁸⁷Sr/⁸⁶Sr and ε<inf>Nd</inf>(0) of the drill bits overlap with those of the Ernestite stones, confirming their genetic relationship. The texture and presence of pseudo-mullite (SiO<inf>2</inf> > 40 wt%) with high Al-Ti-bearing hematite suggest that Ernestites are synthetic, created through a sintering process at ~1100 °C. An abundance of sand to silt-sized detrital quartz, along with Fe-Ti-Zr-rich minerals, indicates the use of unevenly powdered sandstones and laterites as raw materials, with geochemical ties to regional sources.trueArticlehttps://www.nature.com/articles/s40494-025-02147-2.pdf30593220December 202506151WOS:001627820300003