[Pramāṇa](https://indike.org/pramana/) › [Studies](https://indike.org/pramana/ins) › [Science, technology and education](https://indike.org/pramana/ins.science) › [Minerals and Metals in Ancient India](https://indike.org/pramana/ins.science.biswas-1996) › v1.c19.s5.t5.4 # Minerals and Metals in Ancient India v1.c19.s5.t5.4 Minerals and Metals in Ancient India v1.c19.s5.t5.4 - **Language:** English ### [v1.c19.s5.t5.4](https://indike.org/pramana/ins.science.biswas-1996.v1.c19.s5.t5.4) Hegde (1987) examined thin sections of PGW and found ‘insignificantly small number’ of larger and heavier particles of feldspar, quartz or limestone, thus proving the thoroughness of labour that the ancient potters had put in to prepare well-elutriated fine clay before making PGW. Red ochre containing Fe₂O₃ must have been used as the painting medium to decorate PGW before baking in a reducing atmosphere (in a \*gajapuṭa\* type of sealed furnace in which carbonaceous matter burned in an insufficient supply of oxygen producing carbon monoxide) since the black paint on the PGW has been proven to be Fe₃O₄ or magnetite. It is noteworthy that in this PGW era, one further step of reduction of iron oxide led to the first ever production of iron metal in India. - [Previous: v1.c19.s5.t5.3](https://indike.org/pramana/ins.science.biswas-1996.v1.c19.s5.t5.3) - [Next: v1.c19.s5.t5.5](https://indike.org/pramana/ins.science.biswas-1996.v1.c19.s5.t5.5) - [Up: v1.c19.s5.t5](https://indike.org/pramana/ins.science.biswas-1996.v1.c19.s5.t5) --- Source: [https://indike.org/pramana/ins.science.biswas-1996.v1.c19.s5.t5.4](https://indike.org/pramana/ins.science.biswas-1996.v1.c19.s5.t5.4) · Pramāṇa