WEATHERING OF GRANODIORITE MONUMENTS: THE CASE OF A SQUATTING STATUE IN TEMPLE OF KARNAK, LUXOR, EGYPT

During Pharonic times granodiorite was used for architectural purposes such as for the interior structure of temples, for door frames, and as facing stones. For statuary purposes it was used for sarcophagi, and statues, obelisks, stelai, and other such objects. Granodiorite was quarried at Aswan from the Predynastic period to the Roman period. The rocks of the Aswan quarries are of Precambrian age. At this location granodiorite is coarse- to mainly medium-grained, and dark grey to nearly black in colour. Its primary minerals consists of plagioclase feldspar, quartz, alkali feldspar, biotite, and hornblende, the most common accessory minerals include apatite, zircon, sphene, ilmenite, and magnetite. Weathering processes can lead to the transformation of primary minerals in Granodiorite rocks such as micas and feldspars into secondary crystalline and amorphous products. Samples from A deteriorated Granodiorite squatting statue in temple of Karnak were studied by X-Ray diffraction, Polarizing Microscope, Scanning Electron Microscope and Energy dispersive X-ray analysis. It shows that Feldspar minerals were transformed into Kaolinite and sericite as a result of weathering processes. The mafic minerals even more deeply attacked by hydrolysis which creates a myriad of small pits. Micro-fissures caused first by chemical decay, followed by a physical separation of particles along cleavage planes. These deterioration phenomena were found related to many deterioration factors for example, moisture, air pollution and changes in temperature.