In 1966 an excavator of a Bronze Age site in southern Greece concluded that an intense fire destroyed the building he was uncovering. Accordingly, the fire was of such intensity that it melted the limestone and mud (components of the rubble walls) and fused them into a molten mass which then flowed down and covered certain areas of the floor. My questions are, can limestone become a liquid (molten) and if so, at what temperature does it reach such a state?
According to the Handbook of Chemistry and Physics, the mineral aragonite(Calcium carbonate) will decompose at 825 degrees C. Calcite (actually what the limestone would be composed of but also calcium Carbonate) was not listed for 1 atmosphere, but I would guess that it is somewhat similar to the case for aragonite. In any event it does not melt but decomposes to atmospheric carbon dioxide and CaO (calcium oxide, or "quick lime," a powder). Another book said that to form quick lime place limestone in a kiln and cook it at 600 degrees C. Apparently to melt limestone (which I kind of doubt, the handbook said it would melt at 1339 degrees C if at a pressure of 103 atmospheres (no forest fires here). Hope that helps!
Dr. Craig Glenn, Professor
Department of Geology and Geophysics
University of Hawaii, Honolulu, HI 96822
Return to the Ask-An-Earth-Scientist © page