1. Calcium carbonate (CaCO3): Calcium carbonate precipitates in the presence of high concentrations of carbonate ions. It is commonly found in natural waters, such as hard water, and can form scale deposits in pipes and appliances.

2. Calcium phosphate (Ca3(PO4)2): Calcium phosphate precipitates when calcium ions react with phosphate ions. It is a major component of bones and teeth, and its precipitation is influenced by factors such as pH and the concentration of calcium and phosphate ions.

3. Calcium oxalate (CaC2O4): Calcium oxalate precipitates in the presence of high concentrations of oxalate ions. It is a common component of kidney stones and can also be found in urine and other bodily fluids.

4. Calcium sulfate (CaSO4): Calcium sulfate, commonly known as gypsum, precipitates when calcium ions react with sulfate ions. It is found in natural waters, such as groundwater and seawater, and can form scale deposits in pipes and equipment.

5. Calcium fluoride (CaF2): Calcium fluoride precipitates when calcium ions react with fluoride ions. It is less soluble than other calcium salts and is often used in dental products to strengthen teeth and prevent cavities.