Occurrences of Perlite Deposits in Yemen

Abstract

Yemen, which is lies in South West Asia country, in recent years has been known to occasionally produce small quantities of industrial rocks and minerals. Perlite is deposit of comparatively recent interest, it was first described as; a glassy rhyolite, the perlite occurrences are almost always associated with Cenozoic (Tertiary) volcanic rocks of Yemen as; rhyolitic, agglomerate and volcanic tuff, it widespread in various districts in Yemen, among Taiz and Ibb, Thamar districts..etc. Yemeni perlite deposits ranges in colour from greyish black, greenish black to almost black and has vitro¬phyric structures, waxy to pearly luster and resemble obsidian rock futures. The perlitic deposits vary in thickness from a few to tens meters, appears as thick to discontinuous layer-shaped, masses that cover several tenth meters and domes. Petrographic study shows that the Yemeni perlite rocks/ deposits are composed mainly of more than 65% silica groundmass with embedded phenocrysts of quartz, chalcedony, K-feldspars, plagioclase pyroxene, chlorite and iron oxides, showing the similarity with silica groundmass more than 65% Toloshi-Georgian perlite with phenocrysts of chalcedony, orthoclase, sandine, plagioclase, pyroxene, biotite, chlorite and iron oxides. Chemical analysis shows that the majority of studied Yemeni perlite rocks/ deposits have silica content ranging from 69.99 – 73.22 wt.% with an average 71.07 wt.% and water content from 2.04 – 3.30 wt.% with an average 2.96 wt.%, compared with chemical analysis of the Georgian perlite; silica and water content with an average 71.20 wt.% and 3.46 wt.% respectively, while commercial perlite content silica > 65 wt.% and water content range from 2 – 5 wt.%. The uses of expanded perlite are many /varied and based primarily upon its chemical and physical properties where perlite has the unusual characteristic of expanding to about 20 times its original volume when heating up to above 871 °C (1600 °F). Perlite deposits in the Yemen volcanic districts were estimated to have resources of at least 65 – 335 million cubic meters.