Trona is relatively rare, non-metallic mineral, Na2CO3 center dot NaHCO3 center dot 2H(2)O. The pure material contains 70.3% sodium carbonate and by calcination the excess CO2 and water can be driven off, yielding natural soda ash. The terms soda ash and sodium carbonate are used interchangeably. Trona calcining is a key process step in production of soda ash (sodium carbonate anhydrate) from the relatively cheap trona ore. The calcination reaction may proceeds in a sequence of steps. Depending on the conditions, it may result in formation of either sodium carbonate monohydrate (Na2CO3 center dot H2O), sodium sesquicarbonate or weigschederite (Na2CO3 center dot 3NaHCO(3)). The Beypazari Turkish trona deposit is the second largest deposit in the world with the content of 84% trona. The decomposition of trona appeared to be a single stage process across the temperature range studied (150-200 degrees C) with the representative samples of different size fractions in the draught up metallurgical furnace. The optimum particle size and calcination time were-6.35 mm and 30 minutes, respectively, at calcination temperature of 175 degrees C in a metallurgical furnace. Microwave-induced dry calcination of trona was possible and 5 minutes of calcination time at a power level of 900 was sufficient for complete calcination of-6.35 mm feed. This includes short time calcination with the goal of improving economics and simplifying the thermal process.