The question asks for the material used to create the specific sculpture 'Siva Nataraja Performing the nadanta' from Tamil Nadu, dated approximately to c. 12th CE.
South Indian bronze casting, particularly during the Chola period (which aligns with the c. 12th CE timeframe), reached a high level of sophistication. This technique, known as the lost-wax casting method (Maduchhista Vidhana), was widely used to create intricate metal icons, including depictions of deities like Nataraja.
Therefore, the material used for the 'Siva Nataraja Performing the nadanta' sculpture from Tamil Nadu (c. 12th CE) is Bronze.