The main mineral found in limestone is calcium carbonate (CaCO3). Limestone is a sedimentary rock primarily composed of fossilized remains of marine organisms such as coral and shells. This mineral plays a significant role in various geological processes and is commonly used in construction, agriculture, and industry. Calcium carbonate can also react chemically in a process known as carbonation, contributing to the formation of caves and other geological features. Additionally, limestone serves as a crucial raw material for producing lime, which is utilized in multiple applications including water treatment and as a soil conditioner.