Calcite Powder, also known as Limestone Powder, is a naturally occurring sedimentary rock primarily composed of calcium carbonate (CaCO₃) in the mineral form of calcite. It accounts for nearly 10% of all sedimentary rocks found on the Earth’s surface.

Calcite is formed either through direct crystallization from seawater, where calcium ions react with dissolved or atmospheric CO₂ to form insoluble calcium carbonate, or from the accumulation of shells and skeletal fragments of marine organisms. These layers, over time, undergo compaction and lithification, forming solid rock.

Limestone often contains impurities recorded from the chemical composition of seawater, and may include trace minerals such as dolomite (CaMg(CO₃)₂) and aragonite, another crystalline form of calcium carbonate.