In this study and by using available raw materials (clay) for producing lightweight aggregate in order to used them in many construction applications such as producing light weight aggregate concrete for thermal insulating purposes and lightweight in same time and also used them in multistory building as structural materials . This type of lightweight aggregate is called lightweight expanded clay aggregate (Leca) has wide ranges of uses for many reasons , easy to produce and available raw materials and it have good mechanical, physical and chemical properties.This study assesses the possible use of local raw materials (clays) for producing expanded clay pellets and test the product with American standard specifications (ASTM C330), and used it as lightweight aggregate for different construction applications like thermal insulation, lightweight structural concrete , decoration pieces ,etc. The rich calcite clay from Al-Anbar province used in this research to study their heat-treatment behavior. The rich calcite claywas bloated at 1150 C? without adding any impurities ,just mechanical treatment and perfect firing program, in order to obtain good bloating coefficient that is related with firing parameters (temperature , access time, socking time). We was obtained low density aggregate about (448 Kg/m3) from clay I and (280 Kg/m3) from clay II.