In the below map, the black marks show the distribution of

The map historically associated with this question highlights key mineral belts in India, specifically the Hazaribagh-Gaya-Munger belt in Jharkhand and Bihar, Ajmer-Bhilwara in Rajasthan, and Nellore in Andhra Pradesh.

• Mica: India is one of the world's leading producers of mica. The major mica-producing regions precisely match the shaded areas: the Koderma-Giridih-Hazaribagh belt in Jharkhand, the Nellore belt in Andhra Pradesh, and the Ajmer-Bhilwara belt in Rajasthan.
• Gypsum: Predominantly found in the arid regions of western Rajasthan (Bikaner, Jodhpur) and Tamil Nadu.
• Limestone: Widespread across sedimentary basins in states like Madhya Pradesh, Chhattisgarh, and Rajasthan.
• Asbestos: Found mainly in specific districts of Rajasthan and Andhra Pradesh, but does not match the three distinct clusters shown for mica.

Therefore, the black marks on the map indicate the distribution of Mica.