Multianalytical diagnostic approaches for the assessment of materials and decay of the archaeological sandstone of Osiris Temple (The Abaton) in Bigeh Island, Philae (Aswan, Egypt)

Abstract

• Osiris Temple wasn't rescued during UNESCO saving campaign of Aswan temples. • Yellowish and pinkish sandstones are the building materials of the temple. • Fluctuations of Nile water level decayed the temple building materials severely. • Main intrinsic decay factors is the clayed matrix of sandstones. The ancient Osiris Temple at Philae/Aswan, also known as Abaton, was considered one of the most sacred and mysterious temples in Egypt. In 1960, UNESCO rescued Philae temples because the rise of the water level after the construction of the Old and New Dam of Aswan caused the submergence of all temples underwater. Rescue camping was performed to protect all Aswan temples. Unfortunately, Osiris Temple was not rescued and was forgotten in its original place on Bigeh Island. Currently, this temple is subjected to Nile water effects and is partially submerged underwater due to Nile water level changes. This study aims to unravel and assess the conservation state of the temple sandstone-building material through multianalytical and examination techniques (X-ray diffraction, X-ray fluorescence, Raman spectroscopy, polarizing microscopy, binocular microscopy, and scanning electron microscopy). Furthermore, in situ records were obtained, and degradation maps were drawn to establish the patterns of damage and decay of the building material of the Osiris temple. The results showed that blackening, soiling, and disintegration are the dominant decay patterns in the building material of the temple. In addition, the Nile water as an extrinsic factor severely affected the conservation state of the temple due to the continuous exposure to water force. The mineralogical composition of sandstone played an important role in its degradation as an intrinsic decay factor due to mainly dispersion of clayed and/or carbonate matrix dissolution, quartz hydrolysis, and feldspar alteration.