tequesquite

noun

1. A natural mineral salt containing compounds of sodium chlorate and sodium carbonate, used by the Aztecs and later Mexicans as a food seasoning and leavening agent.“The old-fashioned way is to use tequesquite, the naturally occurring form of sodium bicarbonate (sold in many Mexican markets). Because tamales don't contain strongly acidic ingredients, tequesquite's leavening is gentle, producing a lovely but less fluffy texture.”