Thermal Characterization and Mineral Composition of the Egyptian Alabaster “Carbonate Rocks”

Representative rock samples from the banded Egyptian alabaster collected from the Wadi Sannur quarry (53 km SE of Beni Suef, south Cairo). Two distinct bands with a transition zone inbetween. The early crystallized band is white, opaque, and fine-grained. The other band is mostly translucent, coarse?grained and pale-yellowish brown. The participation of the constituents in banded alabaster carbonate rock was determined combining three methods of analysis, microscopic examination, atomic absorption spectroscopy (AAS) and thermogravimetry (TG). The three methods are used in a complimentary way in order to specify the exact composition of each band in the Egyptian alabaster carbonate rock. Calcite represents the main mineral composition in the translucent band, calcite and brucite represnts the main composition of the white one. Calcite and hydromagnesite form the main components of the transition zone but are variable. The percentage of the minerals can be determined with accuracy, only through TG analysis by mass loss. The effect of CO2 and H2O pressure on the temperature reactions has been discussed.