Where is the main geological source of high-purity limestone (calcium carbonate) mined for poultry feed in Pakistan?

In Pakistan, the feed milling industry relies almost entirely on the massive geological deposits of the Salt Range in Punjab for its calcium requirements. High-purity limestone (calcium carbonate, $CaCO_3$, containing 38% to 40% elemental calcium) is extensively mined in the Dandot, Khewra, and Daud Khel regions. This limestone is geological calcite of high chemical purity, characterized by extremely low concentrations of heavy metals such as lead ($Pb$) and cadmium ($Cd$), which can cause chronic toxicity and shell thinness if present. Feed mills crush this limestone into two distinct particle sizes: fine limestone powder (under 100 microns) for rapid daytime calcium absorption and coarse limestone grits (2.0 to 4.0 mm) which remain in the bird's gizzard for slow, nighttime release during eggshell calcification. Farmers can study limestone geology and particle size benefits in the Poultry Encyclopedia, purchase tested limestone grits on Poultry Plaza, monitor daily feed commodity rates on Poultry Rates, and list egg production metrics on Murghi Mandi.