Cancrinite is one constituent of "red muds," a high-volume waste product of alumina production by the Bayer process. The Bureau of Mines determined the thermochemical properties of cancrinite as part of a program to provide such data for minerals of industrial importance. Cancrinite [na7.68(Al6si6o24)(no3)1.68(H20)4.1] was synthesized by reacting aluminum silicate gel with a solution of naoh and nano3, and the composition was determined by chemical analysis, differential scanning calorimetry, and thermogravimetric analysis. The heat of solution was determined by hydrofluoric acid solution calorimetry. The standard enthalpy of formation at 298.15 K, ^hf deg. 298, is ^hf deg. 298 = -3,487.97 +/-2.6 Kcal/mol, and the standard enthalpy of formation from the oxides and nano3, ^h deg. 298, is ^h deg. 298 = -215.20 +/-1.8 Kcal/mol.