Q. Which Jharkhand district is the largest producer of ruby mica?
Answer: Koderma
Notes: Koderma district, established in 1994, is renowned for ruby mica production. It lies in the mica belt extending from Gaya district to Hazaribagh and Koderma. The district holds the richest deposits of high-quality ruby mica with aluminium silicate purity of 95-97%. Jharkhand and Bihar together produce about 25% of the world's mica. Koderma continues to be a major mining center despite mining restrictions from the 1980 Forest Conservation Act.