Petrography and Geochemical Study of the Perlite Rocks from Bait Al-Qeyarie, Kawlan Area, Yemen

Abstract. A sequence of perlite rocks crop out at Bait Al-Qeyarie locality, Kawlan area, which lies at about 60 km SE of Sana’a City. Perlite rocks occur within acidic volcanic rock sequences consisting of rhyolite, greenstone, zeolite, pyroclastic, and tuffaceous rocks. Petrographic examination shows that the perlite rocks are composed mainly of more than 65 % silica groundmass with embedded phenocrysts of quartz, chert, chalcedony, k-feldspar, chlorite, pyroxene and iron oxides. They show onion-skin cracks, the characteristic texture of perlite rocks. Geochemical analysis shows that the majority of the studied perlite rocks have silica content ranging from 65.0 to 75.0 wt%, with an average of 69.6 wt % and water content ranging from 0.35 to 3.94 wt % with an average of 2.14 wt%, compared with the chemical properties of the commercial perlite (silica> 65 wt % and water content range from 2 to 5 wt%). The studied perlite rocks are considered to be of good quality for industrial uses. Their commercial importance comes from their silica-rich groundmass and the combined meteoric water in the structure of the constituent minerals