الفهرس 
Country rocksOnly 14 pages are availabe for public view
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Abstract
The present work deals with the study of the geology, mineralogy and geochemistry of magnesite deposits and their enveloping country rocks at Gabel El - Rubshi and Gabel El - Maiyit, Eastern Desert. It also concerns with the industrial applications of magnesite deposits. The following represent the summary and the concluding remarks of the present study. 5.1. MAGNESITE DEPOSITS AT GABEL EL - RUBSHI Magnesite deposits at Gabel El - Rubshi occur witin ultramafic country rocks consisting of serpentinite, pyroxenite and altered serpentinite rocks. 5.1 .IS.e rpentinite Rocks The fresh serpentinite rocks have dark olive green to greyish green colour with yellowish green tint. The serpentinite rocks were tectonically emplaced within the metasediment and metavolcanic rocks. They were intruded along their southeastern side by an elongated body of unmetamorphosed pyroxenite rocks. Petrographic examination of the serpentinite rocks reveals that the textures of these rocks are represented mainly by pseudomorphic types and describing serpentinites as allofacial ultramafic rocks which belong to the ophiolite of low grade metamorphism (Bucher and Frey, 1994). The encountered pseudomorphic textures are hourglass and mesh types with subordinate bastite texture types, indicating that these serpentinites were derived mainly from peridotite rocks rich in olivine with subordinate orthopyroxene (peridotite of harzburgite composition). The opaque minerals include chromite, magnetite and sulphidg (pentiandite and pyrite). chromite in the serpentinite rocks is the common opaque mineral and represents about 2-6% of the whole rocks. It occurs as rounded and sometimes subhedral grains and streaks, ranging in size from 0.5-1.5 mm. Occasionally, it is brecciated and folded. It is of pale grey with brownish tint. Silicate inclusions are common and are believed to be trapped either during chromite growth (Aug’e, 1987; Lorand and Ceuleneer, 1989) or during post magmatic recrystallization of chromite (Hulbert and von Gruenewaldt, 1985). The chromite grains are replaced by ferilchromite and magnetite. The ferrichromite alteration zones are usually attributed either to process of serpentinization (Spangenberg, 1943) or were formed due to metamorphism (Engin and Aucott, 1971; Bliss and Maclean, 1975 and Ghoneim and Szederkenyi, 1979).