stearate is a carboxylate of calcium, classified as a calcium soap. It is a component of some lubricants, surfactants, as well as many foodstuffs.
It is a white waxy powder
Calcium stearate is produced by heating stearic acid and calcium oxide:
2 C17H35COOH + CaO → (C17H35COO)2Ca + H2O
It is also the main component of soap scum, a white solid that forms when soap is mixed with hard water. Unlike soaps containing sodium and potassium, calcium stearate is insoluble in water and does not lather well. Commercially it is sold as a 50% dispersion in water or as a spray dried powder. As a food additive it is known by the generic E number E470