Probable source of rocks for millstones and cannon balls of Goa, India

The Europeans started to come to India at the beginning of the 16th century for trade. The Portuguese were the first group of Europeans to reach the southwestern coast of India in 1498 and establish their colonies. They were also the last group of the Europeans to leave the Indian territory after ruling a part of the country for about 450 years. With their arrival, new technology and warfare tactics were introduced in the region. Associated with their artillery, preparation of gunpowder as a new technology was introduced in Goa. Gigantic sized millstones were used for the production of gunpowder in Casa de Polvora, Panelim, Goa. In 2007, when real estate developers commenced their construction work at Casa de Polvora, the Archaeological Survey of India salvaged the endangered millstones from Panelim. The aim of the present communication is to analyse the samples and to find out whether the stone used was quarried from Dharavi (Uttan; which was a part of Bassein territory of the Portuguese) from where the Portuguese acquired stones on a large scale for the decoration of churches in Goa. To achieve this, archaeological, petrographic, mineralogical and geochemical studies have been carried out on samples of millstones and the quarried site at Dharavi (Uttan). In addition sample was also collected from cannon ball found at Arsenal (Old Goa) to find out whether stone from Dharavi (Uttan) was used. The analytical results suggest that the millstones are made of limestone, the Dharavi (Uttan) stone is more siliceous - and the cannon balls are made from basalt.