A class of water-base drilling fluid that utilize dissolved Ca⁺² as a component. Examples are lime mud, gyp mud and calcium chloride (CaCl₂) mud. The latter is rarely used, but is based on solutions of CaCl₂ that, in high concentration, can impart density up to 11. 6 lbm/gal (1. 39 g/cm³) and has been touted as providing shale inhibition.