ABSTRACT: Ignimbrite (trass) occurs quite spreadly with in the pyroclasüc deposite of Pliocene age in the southern and western of İsparta. The level of trass depends on a tachiandesite volcanism and it`s thickness which changes between 20-150 m, Trass contains the matrix of glass which composed of feldspar (sanidine, albite), pyroxsene, amfibole, biotite and opac minerals. In addition to various rock pieces, locally carbonized plant remains are other components of the  trass level. The most important feature of the Dereboğazı tass which is used as supplement material in cement production has very high puzolanic activity degree. This value is 103 kgf/cm3 which is high twice of standart value, The Blaine value which is given as 3000 cm/gr at standarts for studies specimens is found 7630 cm/gr, Specific gravity of trass is 2,49 gr/ cm3 and glasslike phase is 40 %. The total amount of SiO2 + A12O3 + Fe2O3 which are taking place at the content of sample trass is between 74-84 %, however MgO, 0,27-0.76 %, SO3, 0,0-0,30 %, The values are very suitable to standart values. In this study we tried to explain; width wide distribution and reserve of the Dereboğazı Trass which is very useful and economic as supplementary material in cement production with it`s all specialities