GEOLOGY, PETROGRAPHY, GEOCHEMISTRY ANDSUITABILITY OF ABU SHEIH PEGMATITE FOR CERAMIC INDUSTRY

The geological, petrographical and geochemical studies as well as physical properties of Abu Sheih pegmatites and its effects on various types of fired ceramic bodies.The rock units in the study area are classified as follow: Wadi deposits (youngest), Post granitic dikes, pegmatite pockets and veins, syenogranites andgranodiorites (oldest).Thegranodiorites are light grey in colour and medium to coarse grained equigranular rocks, composed of plagioclases, quartz, perthites, hornblendebiotite, and muscovite as essential minerals. Zircon, iron oxides, apatite and titanite are accessory minerals whereas epidote as secondary minerals. But syenogranites show distinct pink to red colours. They are medium to coarse grained, hypidiomorphic, possessing subhedral to euhedral crystal faces, they are composed mainly of perthites, quartz, plagioclase, biotite and muscovite as essential minerals, while zircon, titanite, iron oxides and apatite are the accessory minerals. Epidote and chlorite are present as secondary minerals.The geochemical studies revealed that, the studied Granodiorites were originated from metaluminouscalc-alkaline magma intruded in a crust of a thickness less than 30 km at water pressure less than 2 kb. They could be considered as volcanic arc or continental arc granitoides. The Syenogranites were derived from sialic crust and considered as I-type granites, that originated from peraluminous, calc-alkaline, highly fractionated magma. They could be considered as late orogenic granites, intruded in a crust ranging in thickness from 20 km to 30 km.
Pegmatites are relatively enriched in Al2O3and K2O than their granitic host. This is consistent with the mineral composition of pegmatites where they are more enriched in K-feldspar and quartz. Also the depletion of Sr in pegmatites than their granite host is related to less abundant plagioclase in pegmatites.The geochemical studies revealed thatthe studied pegmatite samples classified as granite,subalkaline nature field, intruded in a crust ranging in thickness from 20 to 30 km.