Why were civil war cannon balls made of iron?

Civil War cannonballs were primarily made of iron because it was a durable and readily available material that could withstand the high pressures generated when fired from cannons. Iron cannonballs offered greater density and mass compared to alternatives like stone or lead, allowing for more effective penetration of fortifications and armor. Additionally, iron could be easily cast into the desired shape, making it suitable for mass production during the war. The use of iron also allowed for the incorporation of explosive shells, enhancing their lethality on the battlefield.