| المستخلص: |
One of the most interesting of the monumental rocks of Egypt is the green conglomerates of the Hammamat valley which was used for bowls, vessels, sarcophagus and other objects, from a very early period. The quarries of wadi Hammamat produced the green ornamental stone known in Roman period as "Breccia verde antica". Generally the ancient conglomerate was used occasionally in Egypt at pharaonic time and late period, but it was quarried chiefly by the Roman for export to Italy. The conglomerate rocks range from coarse to fine conglomerates. They are composed of great assortment of rock fragments such as meta-sediments, meta-volcanic and granites. Some pebbles of the coarse conglomerates are previously deposited conglomerates. Pollution, humidity or moisture, solar radiation, rainfall and groundwater represent important factors for disintegration of green conglomerate rocks. Many types of destruction have been noted such as micro-cracks, fractures, joints, exfoliation, crumbling, discoloration, leaching and staining with iron oxides. The conglomerate rock sometimes changes into fragmented, soft residual and parent matter of the soil. Moreover, individual grains of feldspar and quartz begin to become loosened and the rock shows superficial granular disintegration due to, growth of salts and physiochemical weathering. The present work mainly deals with the geology and structural characteristic of conglomerate rocks. It is identify the most important individual changes and the stages of disintegration in the beautiful green conglomerate rocks. In addition, to describe and define the alteration products and deformation of several kinds of pebbles present in the ancient conglomerate rocks. On the other hand, many problems concerning quarrying still remain to be answered at least those concerning the actual techniques used to split the ancient hard rocks. The present study focused on the criteria, quarrying methods and technologies used by the ancient Egyptians in the Hammamat quarries from Pharaonic time to the Roman period. The main results of the different studies which include petrographic microscope, SEM microphotographs and X-Ray diffraction show that the alteration products of the highly weathered ancient conglomerate rocks are dominated by hematite, magnetite, calcite, chlorite, sericite, kaolinite, nantronite, gypsum and anhydrite.
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